FROM the teeth and organs of locomotion, we come next to consider those of digestion in the Ichthyosaurus. If there be any point in the structure of extinct fossil animals, as to which it should have seemed hopeless to discover any kind of evidence, it is the form and arrangement of the intestinal organs; since these soft parts, though of prime importance in the animal economy, yet being suspended freely within the cavity of the body, and unconnected with the skeleton, would leave no traces whatever upon the fossil bones.

It is impossible to have seen the large appa ratus of teeth, and strength of jaws, which we have been examining in the Ichthyosauri, without concluding that animals furnished with such powerful instruments of destruction, must have used them freely in restraining the excessive population of the ancient seas. This inference has been fully confirmed by the recent discovery within their skeletons, of the half digested remains of fishes and reptiles, which they had devoured, (see Pl. 13, 14,), and by the further

[188 INTESTINAL STRUCTURE OF ICHTHYOSAURUS] discovery of Coprolites, (see Pl. 15,) i. e. of foecal remains in a state of petrifaction, dispersed through the same strata in which these skeletons are buried. The state of preservation of these very curious petrified bodies is often so perfect, as to indicate not only the food of the animals from which they were derived, but also the dimensions, form, and structure of their stomach, and intestinal canal.*

On the shore at Lyme Regis, these Coprolites are so abundant, that they lie in some parts of the lias like potatoes scattered in the ground; still

* The following description of these Coprolites, is given in
my memoir on this subject, published in the Transactions of the Geological Society of London, 1829, (vol. iii. N. S. part i. p. 224. with three plates.)

"In variety of size and external form, the Coprolites resemble oblong pebbles or kidney-potatoes. They, for the most part, vary from two to four inches in length, and from one to two inches in diameter. Some few are much larger, and bear a due proportion to the gigantic calibre of the largest Ichthyosauri; others are small, and bear a similar ratio to the more infantine individuals of the same species, and to small fishes: some are flat and amorphous, as if the substance had been voided in a semifluid state; others are flattened by pressure of the shale. Their usual colour is ash grey, sometimes interspersed with black, and sometimes wholly black. Their substance is of a compact earthy texture, resembling indurated clay, and having a conchoidal and glossy fracture. The structure of the Coprolites at Lyme Regis is in most cases tortuous, but the number of coils is very unequal; the most common number is three: the greatest I have seen is six: these variations may depend on the various species of animals from which they are derived; I find analogous variations in the tortuous intestines of modern Skates, Sharks, and Dog-fish. Some

[189 COPROLITES.] more common are they in the lias of the Estuary of the Severn, where they are similarly disposed in strata of many miles in extent, and mixed so abundantly with teeth and rolled fragments of the bones of reptiles and fishes, as to show that this region, having been the bottom of an ancient sea, was for a long period the receptacle of the bones and foecal remains of its inhabitants. The occurrence of Coprolites is not however peculiar to the places just mentioned, they are found in greater or less abundance throughout the lias of England; they occur also in strata, of all

Coprolites, especially the small ones, show no traces at all of contortion.

" The sections of these fœcaI balls, (see Pl. 15, Figs. 4, and 6,) show their interior to be arranged in a folded plate, wrapped spirally round from the centre outwards, like the whorls of a turbinated shell; their exterior also retains the corrugations and minute impressions, which, in their plastic state, they may have received from the intestines of the living animals. (See Pl. 15, Figs. 3, and 10 to14.) Dispersed irregularly and abundantly throughout these petrified feces, are the scales, and occasionally the teeth and bones of fishes, that seem to have passed undigested through the bodies of the Saurians; just as the enamel of teeth and sometimes fragments of bone, are found undigested both in the recent and fossil album græcum of hyænas. These scales are the hard bright scales of the Dapediurn polztum, and other fishes which abound in the lias, and which thus appear to have formed no small portion of the food of the Saurians. The bones are chiefly vertebræ of fishes and of small Ichthyosauri; the latter are less frequent than the bones of fishes, but still are sufficiently numerous, to show that these monsters of the ancient deep, like many of their successors in our modern oceans, may have devoured the small and weaker individuals of their own species."

[190 INTESTINAL STRUCTURE OF ICHTHYOSAURUS] ages that contain the remains of carnivorous reptiles, and have been recognized in many and ditant regions both of Europe and America.*

The certainty of the origin of these Coprolites is established, by their frequent presence in the abdominal region of fossil skeletons of Ichthyosauri found in the lias of Lyme Regis. One of the most remarkable of these is represented in Pl. 13; the coprolitic matter loaded with fish scales, within the ribs of these and similar specimens, is identical in appearance and chemical composition with the insulated coprolites that occur in the same strata with the skeletons.

Professor Jæger has recently discovered many Coprolites in the alum slate of Gaildorf in Wirtemberg; a formation which he considers to be in the lower region of that part of the new red sandstone formation which in Germany is called Keuper; and which contains the remains of two species of Saurians.

In the United States Dr. Dekay has also discovered Coprolites in the Green-sand formation of Monmouth, in New Jersey, see Pl. 15,Fig. 13.

This specimen has been presented by Viscount Cole to the Geological Collection of the University of Oxford. It affords decisive proof that the substances in question cannot be referred to adventitious matter, placed accidentally in contact with the fossil body, inasmuch as the large coprolitic mass is enclosed between the back bone and the right and left series of the ribs, of which the greater number remain nearly in their natural position. The quantity of this coprolite is prodigious, when compared with the size of the animal in which it occurs; and if we were not acquainted with the powers of the digestive organs of reptiles and fishes, and their capacity of gorging the larger animals that form their prey; the great space within these fossil skeletons of Ich thyosauri, which is occasionally filled with coprolitic matter, would appear inexplicable.

[191 COPROLITES.] The preservation of such fœcal matter, and its conversion to the state of stone, result from the imperishable nature of the phosphate of lime, of which both bones, and the products of digested bones are equally composed.

The skeleton of another Ichthyosaurus in the Oxford Museum, from the lias at Lyme Regis, (Pl. 14) shows a large mass of fish scales, chiefly referrible [sic] to the Pholidophorus limbatus,* intermixt with coprolite throughout the entire region of the ribs; this mass is overlaid by many ribs, and although, in some degree perhaps, extended by pressure, it shows that the length

* According to Professor Agassiz, the scales of Pholidophorus limbatus, a species very frequent among the fossils of the lias, are more abundant than those of any other fish in the Coprolites found in that formation at Lyme Regis; and show that this species was the principal food of these reptiles. In Coprohites from the coal formation, near Edinburgh, he has also recognized the scales of Palæoniscus, and of other fishes that are often found entire in strata that accompany the coal of that neighbourhood. Scales of the Zeus Lewisiensis, a fish discovered by Mr. Mantell, in the chalk, occur in Coprohites derived from voracious fishes during the deposition of this formation.

A Coprohite from the lias, (Pl. 15, Fig. 3), remarkable for its spiral convolutions, and vascular impressions, affords a striking example of the minute accuracy with which investigations are now conducted by naturalists, and of the kind of evidence which comparative anatomy contributes in aid of geological enquiry. On one side of this Coprohite, there is a small scale, (Fig. 3, a,) which I could only refer to some unknown fish, of the numerous species that occur in the lias. The instant I showed it to M. Agassiz, he not only pronounced its species to be the Pholidophorus limbatus; but at once declared the precise place which this scale had occupied upon the body of the fish. A minute

[192 INTESTINAL STRUCTURE OF ICHTHYOSAURUS] of the stomach was nearly co-extensive with the trunk.

Among living voracious reptiles we have examples of stomachs equally capacious; we kuow that whole human bodies have been found within the stomachs of large Crocodiles; we know also, from the form of their teeth, that the Ichthyosauri like the Crocodiles, must have gorged their prey entire; and when we find, imbedded in Coprolites derived from the larger Ichthyosauri, bones of smaller Ichthyosauri, of such dimensions, (see Pl. 15, Fig. 18. And Geol. Trans. 2, S. vol. iii, Pl. 29, Figs. 2, 3, 4, 5,) that the individuals from which they were derived, must have measured several feet in length; we infer that the stomach of these animals formed a pouch, or sac, of prodigious size, extending through nearly the entire cavity of the body, and of capacity duly proportioned to the jaws and teeth with which it co-operated.

tube upon its inner surface, (Pl. 15, Fig. 3',) scarcely visible without a microscope, showed it to have been one of those which form the lateral line of perforated scales, that pass from the head towards the tail, one on each side of every fish; and convey a tube for the transmission of lubricating mucus from glands in the head, to the extremity of the body. The place of the scale in this line, had been on the left side, not far from the head. Fig. 3" is the upper surface of a similar scale, showing at e the termination of the mucous duct.

[193 COPROLITES.]

As,the more solid parts of animals alone, are usually susceptible of petrifaction, we cannot demonstrate by direct evidence the form and size of the small intestines of the Ichthyosauri, but the contents of these viscera are preserved in such perfection in a fossil state, as to afford circumstantial evidence that the bowels in which they were moulded, were formed in a manner resembling the spiral intestines of some of the swiftest and most voracious of our modern fishes.

We shall best understand the structure of these intestines by examining the corresponding organs of Sharks and Dog-fish, animals not less peculiarly rapacious among the inhabitants of our modern seas, than the Ichthyosauri were in those early periods to which our considerations are carried back. We find in the intestines of these fishes, (see Pl. 15, Figs. 1, and 2,) and also in those of Rays, an arrangement resembling that of the interior of an Archimedes screw, admirably adapted to increase the extent of internal surface for the absorption of nutriment from the food, during its passage through a tube containing within it a continuous spiral fold, coiled in such a manner, as to afford the greatest

[194 INTESTiNAL STRUCTURE OF ICHTHYOSAURUS.]

possible extent of surface in the smallest space. A similar contrivance is shown by the Coprolites to have existed in the Ichthyosaurus. See Pl. 15, Figs. 3, 4, 6.*

Besides the spiral structure and consequent shortness of the small intestine, we have additional evidence to show even the form of the minute vessels and folds of the mucous

* These cone-shaped bodies are made up of a flat and continuous plate of digested bone, coiled round itself whilst it was yet in a plastic state. The form is nearly that which would be assumed by a piece of riband, forced continually forward into a cylindrical tube, through a long aperture in its side. In this case, the riband moving onwards, would form a succession of involuted cones, coiling one round the other, and after a certain number of turns within the cylinder, (the apex moving continually downwards,) these cones would emerge from the end of the tube in a form resembling that of the Coprolites, Pl. 15, Figs. 3, 5, 7, 10, 11, 12, 13, 14. In the same manner, a lainina of coprolitic matter would be coiled up spirally into a series of successive cones, in the act of passing from a small spiral vessel into the adjacent large intestine. Coprolites thus formed fell into soft mud, whilst it was accumulating at the bottom of the sea, and together with this mud, (which has subsequently been indurated into shale and stone,) they have undergone so complete a process of petrifaction, that in hardness, and beauty of the polish of which they are susceptible, they rival the qualities of ornamental marble.

Fig. 6, shows a longitudinal section through the axis of

[196 COPROLITES. membrane, by which it was lined. This evidence consists in a series of vascular impressions and corrugations on the surface of the Coprolite, which it could only have received during its passage through the windings of this flat tube.* Specimens thus marked are engraved at Pl. 15, Figs. 3, 5, 7, 10, 12, 13, 14.

If we attempt to discover a final cause for these curious provisions in the bowels of the extinct reptile inhabitants of the seas of a former world, we shall find it to be the same that explains the existence of a similar structure

a coprolite, from the inferior chalk, in which this involute conical form is well defined. Fig. 4, is the transverse section of another Coprolite from the lias, showing the manner in which the plate coils round itself, till it terminates externally in a broken edge, at (b). In all the figures the letter b, marks the transverse section of this plate, where it is broken off near the termination of its outer coil; the sections at b, show also the size and form of the flattened passage through the interior of the screw.

A lamina of tenacious plastic substance pressed continually forwards from the interior of such a screw, into the cavity of the large intestine, would coil up spirally within it, until it attained the largest size admitted by its diameter; from this coil successive portions would be broken off abruptly, at (b,) and descending into the cloaca would be thence discharged into the sea.

These impressions cannot have been derived from the mem brane of the inferior large intestine, because they are continued along those surfaces of the inner coils of the Coprolite, which became permanently covered by its outer coils, in the act of passing from the spiral tube into this large intestine.

[196 INTESTINAL STRUCTURE OF ICHTHYOSAURUS] in the modern voracious tribes of Sharks and Dog-fish.*

As the peculiar voracity of all these animals required the stomach to be both large and long, there would remain but little space for the smaller viscera; these are therefore reduced, as we have seen, nearly to the state of a flattened tube, coiled like a corkscrew around itself; their bulk is thus materially diminished, whilst the amount of absorbing surface remains almost the same, as if they had been circular. Had a large expansion of intestines been superadded to the enormous stomach and lungs of the Ichthyosaurus, the consequent enlargement of the body would have diminished the power of progressive motion, to the great detriment of an

* Paley, in his chapter on mechanical compensations in the structure of animals, mentions a contrivance similar to that which we attribute to the Ichthyosaurus, as existing in a species of Shark, (the Alopecias, Squalus Vulpes, or Sea Fox). "In this animal, he says, the intestine is straight from one end to the other: but, in this straight, and consequently short intestine, is a winding, cork-screw, spiral passage, through which the food, not without several circumvolutions, and in fact by a long route, is conducted to its exit. Here the shortness of the gut is compensated by the obliquity of the percoration."

Dr. Fitton has called my attention to a passage in Lord King's Life of Locke, 4° p. 166, 167, from which it appears that the importance of a spiral disposition within the intestinal canal, which he observed in many preparations in the collection of anatomy at Leyden, was duly appreciated by that profound philosopher.

[197 COPROLITES.] animal which depended on its speed for the capture of its prey.

The above facts which we have elicited from the coprolitic remains of the Ichthyosauri, afford a new and curious contribution to our knowledge both of the anatomy and habits of the extinct inhabitants of our planet. We have found evidence which enables us to point out the existence of beneficial arrangements and compensations, even in those perishable, yet important parts which formed their organs of digestion. We have ascertained the nature of their food, and the form and structure of their intestinal canal; and have traced the digestive organs through three distinct stages of descent, from a large and long stomach, through the spiral coils of a compressed ileum, to their termination in a cloaca; from which the Coprolites descended into the mud of the nascent lias. In this lias they have been interred during countless ages, until summoned from its deep recesses by the labours of the Geologist, to give evidence of events that passed at the bottom of the ancient seas, in ages long preceding the existence of man.

[198 INTESTINAL STRUCTURE]

Discoveries have recently been made of Coprolites derived from fossil fishes. Mr. Mantell has found them within the body of the Macropoma Mantellil, from the chalk of Lewes, placed in contact with the long stomach of this voracious fish: the coats of its stomach are also well preserved.* Miss Anning also has discovered them within the bodies of several species of fossil fish, from the lias at Lyme Regis. Dr. Hibbert has shown that the strata of fresh-water limestone, in the lower region of the coal formation, at Burdie House, near Edinburgh, are abundantly interspersed with Coprolites, derived from fishes of that early era; and Sir Philip Egerton has found similar fæcal remains, mixed with scales of the Megalichthys, and fresh-water shells, in the coal formation of Newcastle-under-Lyne. In 1832, Mr. W. C. Trevelyan recognized Coprolites in

* See Mantell's Geol. of Sussex, Pl. 38. I learn from Mr. Mantell, that the form of the Coprolites within the Macropoma most nearly resemble those engraved, Pl. 15, Figs. 8, 9, of the present work: he also conjectures that the more tortuous kinds, (Pl. 15, Figs . 5, 7), long known by the name of Juli, and supposed to be fossil fir cones, may have been derived from fishes of the Shark family, (Ptychodus) whose large palatal teeth (Pl. 27.f) abound in the same localities of the chalk formation With them, at Steyning and Hamsey.

[199 OF FOSSIL FISHES.] the centre of nodules of clay ironstone, that abound in a low cliff composed of shale, belonging to the coal formation at Newhaven, near Leith. I visited the spot, with this gentleman and Lord Greenock, in September, 1834, and found these nodules strewed so thickly upon the shore, that a few minutes sufficed to collect more specimens than I could carry; many of these contained a fossil fish, or fragment of a plant, but the greater number had for their nucleus, a Coprolite, exhibiting an internal spiral structure; they were probably derived from voracious fishes, whose bones are found in the same stratum. These nodules take a beautiful polish, and have been applied by the lapidaries of Edinburgh to make tables, letter presses, and ladies' ornaments, under the name of Beetle stones, from their supposed insect origin. Lord Greenock has discovered, between the laminæ of a block of coal, from the neighbourhood of Edinburgh, a mass of petrified intestines distended with Coprolite, and surrounded with the scales of a fish, which Professor Agassiz refers to the Megalichthys.

This distinguished naturalist has recently ascertained that the fossil worm-like bodies, so abundant in the lithographic slate of Solenhofen, and described by Count Münster in the Petrefacten of Goldfuss, under the name of Lumbricaria, are either the petrified intestines

[200 INTESTINAL STRUCTURE OF FOSSIL FISHES,] of fishes, or the contents of their intestines, still retaining the form of the tortuous tube in which they were lodged. To these remarkable fossils he has given the name of Cololites. (Pl. 15' is copied from one of a series that are engraved in Goldfuss. Petrefacten, Pl. 66.) He has also found similar tortuous petrifactions within the abdominal cavity of fossil fishes, belonging to several species of the genus Thrissops and Leptolepis, occupying the ordinary position of the intestines between the ribs.* (See Agassiz Poissons Fossiles, liv. 2, Appendix, p. 15.)

* As these Cololites are most, frequently found insulated in the lithographic limestone, M. Agassiz has ingeniously explained this fact by observing the process of decomposition of dead fishes in the lakes of Switzerland. The dead fish floats on the surface, with its belly upwards, until the abdomen is so distended with putrid gas, that it bursts: through the aperture thus formed the bowels come forth into the water, still adhering together in their natural state of convolution. This intestinal mass is soon torn from the body by the movement of the waves; the fish then sinks, and the bowels continue a long time floating on the water: if cast on shore, they remain many days upon the sand before they are completely decomposed. The small bowels only are thus detached from the body, the stomach and other viscera remain within it.

We owe this illustration of the nature of these fossil bodies, whose origin has hitherto been inexplicable, to the author of a most important work on fossil fishes, now under publication at Neuchatel. His qualifications for so great and difficult a task are abundantly guaranteed by the fact, that Cuvier, on seeing the progress he had made, at once placed at the disposal of Professor Agassiz the materials he had himself collected towards a similar work.

[201 COLOLITES.] It is probable that to many persons inexperienced in anatomy, any kind of information on a subject so remote, and apparently so inaccessible, as the intestinal structure of an extinct reptile or a fossil fish, may at first appear devoid of the smallest possible importance; but it assumes a character of high value, in the investigation of the proofs of creative wisdom and design, that are unfolded by the researches of Geology; and supplies a new link to that important chain, which connects the lost races that formerly inhabited our planet, with species that are actually living and moving around ourselves.*  The systematic recurrence, in animals of such distant eras, of the same contrivances, similarly disposed to effect similar purposes, with analogous adaptations to peculiar conditions of existence, shows that they all originated in the same Intelligence.

When we see the body of an Ichthyosaurus, still containing the food it had eaten just before its death, and its ribs still surrounding the remains of fishes, that were swallowed ten thousand,

* Le temps qui répand de Ia dignité sur tout ce qui échappe à son pouvoir destructeur, fait voir ici un exemple singulier de son influence: ces substances si viles dans leur origine, étant rendues à la lumière après tant de siècles, deviennent d'une grande importance puis qu'elles servent à remplir un nouveau chapitre dans l'histoire naturelle du globe. — Bulletin Soc. Imp. de Moscow, No. VI. 1833, p. 23.

[202 MARINE SAURIANS.] or more than ten times ten thousand years ago, all these vast intervals seem annihilated, time altogether disappears, and we are almost brought into as immediate contact with events of immeasurably distant periods, as with the affairs of yesterday.
 
 

WE come next to consider a genus of extinct animals, nearly allied in structure to the Ichthyosaurus, and co-extensive with it through the middle ages of our terrestrial history. The discovery of this genus forms one of the most important additions that Geology has made to comparative anatomy. It is of the Plesiosaurus, that Cuvier asserts the structure to have been the most heteroclite, and its characters altogether the most monstrous, that have been yet found amid the ruins of a former world. To the head of a Lizard, it united the teeth of a Crocodile; a neck of enormous length, resembling the body of a Serpent: a trunk and tail having the proportions of an ordinary quadruped, the ribs of a

* See Pl. 16, 17, 18, 19.
Cet habitant de l'ancien monde est peut-être la plus hétéroclite et celui de tous qui paroit le plus mériter le nom de monstre. — Oss. Foss. V. Pt. 2, p. 476.

[203 PLESIOSAURUS,] Camelion, and the paddles of a Whale. Such are the strange combinations of form and structure in the Plesiosaurus — a genus, the remains of which, after interment for thousands of years amidst the wreck of millions of extinct inhabitants of the ancient earth, are at length recalled to light by the researches of the Geologist, and submitted to our examination, in nearly as perfect a state as the bones of species that are now existing upon the earth.

The Plesiosauri appear to have lived in shallow seas and estuaries, and to have breathed air like the Ichthyosauri, and our modern Cetacea. We are already acquainted with five or six species, some of which attained a prodigious size and length; but our present observations will be chiefly limited to that which is the best known, and perhaps the most remarkable of them all, viz, the P. Dolichodeirus.*

* The first specimens of this animal were discovered in the lias of Lyme Regis, about the year 1823, and formed the foundation of that admirable paper (Geol. Trans. Lond. vol. 5, Pt. 2.) in which Mr. Conybeare and M. De la Beche established and named this genus. Other examples have since been recognized in the same formations in different parts of England, Ireland, France, and Germany, and in formations of various ages, from the muschel kalk upwards to the chalk. The first specimen discovered in a state approaching to perfection, was that in the collection of the Duke of Buckingham, (figured in the Geol. Trans. Lond. N. S. Vol. 1, Pt. 2, Pl. 48). Another specimen, nearly entire, in the collection of the British Museum, eleven feet in length, is figured in our second volume, (Pl. 16); and at Pl. 17, a still more

[204 MARINE SAURIANS.]

The head of the P. Dolichodeirus exhibits a combination of the characters of the Ichthyosaurus, the Crocodile, and the Lizard, but most nearly approaches to the latter. It agrees with the Ichthyosaurus in the smallness of its nostrils, and also in their position near the anterior angle of the eye; it resembles the Crocodile, in having the teeth lodged in distinct alveoli; but differs from both, in the form and shortness of its head, many characters of which approach closely to the Iguana.

perfect fossil skeleton, also in the British Museum, discovered by Mr. Hawkins, in the lias at Street, near Glastonbury. At Pl. 16 is also copied Mr. Conybeare's restoration of this animal, from dislocated fragments, before any entire skeletons were found. The near approach of this restoration to the character of the perfect skeletons, affords a striking example of the sure grounds on which comparative anatomy enables us to reconstruct the bodies of fossil animals, from a careful combination of insulated parts. The soundness of the reasoning of Cuvier, on the fossil quadrupeds of Montmartre, was established by the subsequent discovery of skeletons, such as he had conjecturally restored from insulated bones. Mr. Conybeare's restoration of the Plesiosaurus Dolichodeirus, (Pl. 16,) was not less fully confirmed by the specimens above mentioned.

* See Pl. 16, 17, 18.

Mr. Conybeare, in the Geol. Trans. second series, vol. 1, part 1, Pl. 19, has published figures of the superior and lateral view of a nearly perfect head of this animal. Our figure, Pl. 18, Fig. 2, represents the head of the specimen in the British Museum,

[205 PLESIOSAURUS.]

The most anomalous of all the characters of P. Dolichodeirus is the extraordinary extension of the neck, to a length almost equalling that of the body and tail together, and surpassing in the number of its vertebræ (about thirty-three) that of the most long-necked bird, the Swan: it thus deviates in the greatest degree from the almost

of which the entire figure, on a smaller scale, is given in Pl. 16. The head is in a supine position; the upper jaw is distorted, and shows several of the separate alveoli that contained the teeth, and also the posterior portion of the palate. The under jaw is but little disturbed.

A figure of another lower jaw is given at Pl. 18, Fig. 1, taken from a specimen also in the British Museum, found by Mr. Hawkins, at Street.

Pl. 19, Fig. 3, represents the extremity of the dental bone of another lower jaw, in the same collection, retaining several teeth in the anterior sockets, and also exhibiting a series of new teeth, rising within an interior range of small cavities. This arrangement for the formation of new teeth, in cells within the bony mass that contains the older teeth, from which they shoot irregularly forwards through the substance of the bone, forms an important point of resemblance whereby the Plesiosaurus as sumes, in the renovation of its teeth, the character of Lizards, combined with the position of the perfect teeth in distinct alveoli, after the manner of Crocodiles.

The number of teeth in the lower jaw was fifty-four, which, if met by a corresponding series in the upper jaw, must have made the total number to exceed one hundred. The anterior part of the extremity of the jaw enlarges itself like the bowl of a spoon, to allow space for the reception of' the six first teeth on each side, which are the largest of all.

[206 MARINE SAURIANS.] universal law, which limits the cervical vertebræ of quadrupeds to a very small number. Even in the Camelopard, the Camel, and Lama, their number is uniformly seven. In the short neck of the Cetacea the type of this number is maintained. In Birds it varies from nine to twenty-three; and in living Reptiles from three to eight.* We shall presently find in the habits of the Plesiosaurus a probable cause for this extraordinary deviation from the normal character of the Lizards.

* To compensate for the weakness that would have attended this great elongation of the neck, the Plesiosaurus had an addition of a series of hatchet-shaped processes, on each side of the lower part of the cervical vertebrce. (Pl. 17, and Pl. 19, 1, 2.) Rudiments and modifications of these processes exist in birds, and in long-necked quadrupeds. In the Crocodiles they assume a form, most nearly approaching that which they bear in the Plesiosaurus.

The bodies of the vertebrae also more nearly resemble those of certain fossil Crocodiles, than of Ichthyosauri or Lizards; they agree further with the Crocodile, in having the annular part attached to the body by sutures; so that we have in the neck of the P. Dolichodeirus a principle of construction resembling that of the vertebræ of Crocodiles; combined with an elongation very much exceeding that of the longest neck in birds, and such as occurs in no other known animal of the extinct or living creations. The length of the neck in P. Dolichodeirus is nearly live times that of the head; that of the trunk four times the length of the head, and of the tail three times; the head itself being one-thirteenth part of the whole body. — See Geol. Trans. Lond. Vol. 5, p. 559,and Vol. l. N. S. p. 103, et seq.

[207 PLESIOSAURUS.]

The vertebræ of the back were not disposed in hollow cones, like those of fishes, but presented to each other nearly flat surfaces, giving to the column a stability, like that which exists in the back of terrestrial quadrupeds. The articulating processes, also, were locked into one another in such manner as to give strength, rather than that peculiar kind of flexibility, which admitted of the same quick progressive motion in the Ichthyosauri that we find in fishes: but as rapid motion was incompatible with the structure of the other parts of the Plesiosaurus, the combination of strength, rather than of speed with flexibility, was more important.

The tail, being comparatively short, could not have been used like the tail of fishes, as an instrument of rapid impulsion in a forward direction; but was probably employed more as a rudder, to steer the animal when swimming on the surface, or to elevate or depress it in ascending and descending through the water. The same consequence as to slowness of motion would follow from the elongation of the neck, to so great a distance in front of the anterior paddles. The total number of vertebrae in the entire column was about ninety. From all these circumstances we may infer that this animal, although of considerable size, had to seek its food,

[208 MARINE SAURIANS.] as well as its safety, chiefly by means of artifice and concealment.

The ribs are composed of two parts, one vertebral and one ventral; the ventral portions of one side, (Pl. 18, 3, b,) uniting with those on the opposite side by an intermediate transverse bone, (a, c,) so that each pair of ribs encircled the body with a complete belt, made up of five parts. Cuvier observes that the similarity of this structure to that of the ribs of Cameleons and two species of Iguana, (Lacerta Marmorata, Lin. and Anolius, Cuvier,) seems to show that the lungs of the Plesiosaurus Dolichodeirus, (as in these three sub-genera of living Saurians,) were very large; and possibily that the colour of its skin also was changeable, by the varied intensity of its inspirations. Oss. Foss. Vol. V. Pt. 2. p. 280.

*See Pl. 16, 17, 18.

The ventral portion of each rib, (Pl. 17, and Pl. 18, 3, b,) appears to have been composed of three slender bones fitted to one another by oblique grooves, allowing of great expansive movement during the inflation of the lungs the manner in which these triple bones were folded over one another, is best seen in a single series between a, and b, the upper ends of the ventral portions of the ribs (b) have been separated by pressure, from the lower ends of the vertebral portions. (d.)

We have no means to verify this ingenious conjecture, that the Plesiosaurus may have been a kind of sub-marine Cameleon,

[209 PLESIOSAURUS.] This hypothesis of Cuvier is but conjectural, respecting the power of the Plesiosaurus to change the colour of its skin; and to the unexperienced in comparative anatomy, it may seem equally conjectural, to deduce any other conclusions respecting such perishable organs as the lungs, from the discovery of peculiar con- trivances, and unusual apparatus in the ribs; yet we argue on similar grounds, when from the form and capabilities of these fossil ribs, we infer that they were connected, as in the cameleon, with vast and unusual powers of expansion and contraction in the lungs; and when, on finding the ribs and wood-work of a worn-out bellows, near the ruins of a blacksmith's forge, we con clude that these more enduring parts of the

possessing the power of altering the colour of its skin; it must however be admitted that such a power would have been of much advantage to this animal, in defending it by concealment from its most formidable enemy the Ichthyosaurus, with which, its diminutive head and long slender neck, must have rendered it a very unequal combatant, and from whose attacks its slow locomotive powers must have made escape by flight impossible; the enlarged condition of the lungs, would also have been of great advantage in diminishing the frequency of its ascents to the surface, to inspire air; an operation that must have been attended with constant danger, in a sea thickly swarming with lchthyosauri. Dr. Stark has recently observed that certain fishes, especially minnows, have a tendency to assume the colour of the vessel in which they are kept. (Proceedings Zool. Soc. Lond. July, 1833.) As in animals of this class there are no lungs, this change of colour must arise from other cause than that to which it has been attributed in the Cameleon.

[210 MARINE SAURIANS.] frame of th is instrument, have been connected with a proportionable expansion of leather.

The compound character of the ribs, probably  also gave to the Plesiosaurus the same power of' compressing air within its lungs, and in that state taking it to the bottom, which we have considered as resulting from the structure of the steno-costal apparatus of the Ichthyosauri.

As the Plesiosaurus breathed air, and was therefore obliged to rise often to the surface for inspiration, this necessity was met by an apparatus in the chest and pelvis, and in the bones of the arms and legs, enabling it to ascend and descend in the water after the manner of the Ichthyosauri and Cetacea; accordingly the legs were converted into paddles, longer and more powerful than those of the Ichthyosaurus, thus  compensating for the comparatively small assistance which it could have derived from its tail.

Comparing these extremities with those of other vertebrated animals, we trace a regular

* See Pl. 16, 17, 19.
The number of joints representing the phalanges of the fingers and toes exceeds that in the Lizards and Birds, and also in all Mammalia, excepting the Whales, some of which present a similar increase of number to accommodate them to the corresponding office of a paddle. The mode of connection between the joints was (like that in the Whales,) by synchondrosis. The phalanges of the Plesiosaurus present a link, between the

[211 PLESIOSAURUS.] series of links and gradations, from the corresponding parts of the highest mammalia, to their least perfect form in the fins of fishes. In the fore paddle of the Plesiosaurus, we have all the essential parts of the fore leg of a quadruped, and even of a human arm; first the scapula, next the humerus, then the radius and ulna, succeeded by the bones of the carpus and metacarpus, and these followed by five fingers, each composed of a continuous series of phalanges. (see Pl. 16, 17, 19.) The hind paddle also offers precisely the same analogies to the leg and foot of the Mamnmalia; the pelvis and femur are succeeded by a tibia and fibula, which articulate with the bones of the tarsus and metatarsus, followed by the numerous phalanges of five long toes.

From the consideration of all its characters, Mr. Conybeare has drawn the following inferences with respect to the habits of the Plesiosaurus Dolichodeirus, " That it was aquatic is evident, from the form of its paddles; that it was marine is almost equally so, from the remains with which it is universally associated;

still more numerous and angular joints of the paddle of the lchthyosaurus, and the phalanges of land quadrupeds, which are more or less cylindrical; in these sea Lizards they were flattened, for the purpose of giving breadth to the extremities as organs of swimming. As its paddles give no indication of having carried even such imperfect claws, as those of t.he Turtles and Seals, the Plesiosaurus apparently could have made little or no progress in any other element than water.

[212 MARINE SAURIANS.] that it may have occasionally visited the shore, the resemblance of its extremities to those of the Turtle may lead us to conjecture; its motion however must have been very awkward on land; its long neck must have impeded its progress through the water; presenting a striking contrast to the organization which so admirably fits the Ichthyosaurus to cut through the waves. May it not therefore be concluded (since, in addition to these circumstances, its respiration must have required frequent access of air,) that it swam upon, or near the surface, arching back its long neck like the swan, and occasionally darting it down at the fish which happened to float within its reach. It may perhaps have lurked in shoal water along the coast, concealed among the sea-weed, and raising its nostrils to a level with the surface from a considerable depth, may have found a secure retreat from the assaults of dangerous enemies; while the length and flexibility of its neck may have compensated for the want of strength in its jaws, and its incapacity for swift motion through the water, by the suddenness and agility of the attack which they enabled it to make on every animal fitted for its prey, which came within its reach." — Geol. Trans. N. S. vol. i. part ii. p. 388.

We began our account of the Plesiosaurus with quoting the high authority of Cuvier, for considering it as one of the most anomalous and monstrous productions of the ancient systems of

[213 PLESIOSAURUS.] creation; we have seen in proceeding through our examination of its details, that these apparent anomalies consist only in the diversified arrangement, and varied proportion, of parts fundamentally the same as those that occur in the most perfectly formed creatures of the present world.

Pursuing the analogies of construction, that connect the existing inhabitants of the earth with those extinct genera and species which preceded the creation of our race, we find an unbroken chain of affinities pervading the entire series of organized beings, and connecting all past and present forms of animal existence by close and harmonious ties. Even our own bodies, and some of their most important organs, are brought into close and direct comparison with those of reptiles, which, at first sight, appear the most monstrous productions of creation; and in the very hand and fingers with which we write their history, we recognise the type of the paddles of the Iclithyosaurus and Plesiosaurus.

Extending a similar comparison through the four great classes of vertebral animals, we find in each species a varied adaptation of analogous parts, to the different circumstances and conditions in which it was intended to be placed. Ascending from the lower orders, we trace a gradual advancement in structure and office, till we arrive at those whose functions

[214 MARINE SAURIANS.] are the most exalted: thus, the fin of the fish becomes the paddle of the reptile Plesiosaurus and Ichthyosaurus; the same organ is converted into the wing of the Pterodactyle, the bird and bat; it becomes the fore-foot, or paw, in quadrupeds that move upon the land, and attains its highest consummation in the arm and hand of rational man.

I will conclude these observations in the words and with the feelings of Mr. Conybeare, which must be in unison with those of all who have had the pleasure to follow him through his masterly investigations of this curious subject, from which great part of our information respecting the genus Plesiosaurus has been derived:

" To the observer actually engaged in tracing the various links that bind together the chain of organized beings, and struck at every instant by the development of the most beautiful analogies, almost every detail of comparative anatomy, however minute, acquires an interest, and even a charm; since he is continually presented with fresh proof of the great general law, which Scarpa himself, one of its most able investigators, has so elegantly expressed: 'Usque adeo natura, una eadem semper atque multiplex, dis paribus etiam formis effectus pares, admirabili quadam varietatuin simplicitate conciliat.'"

[215 MOSASAURUS.]

THE Mosasaurus lias been long known by the name of the great animal of Maestricht, occurring near that city, in the calcareous freestone which forms the most recent deposit of the cretaceous formation, and contains Ammonites, Belemnites, Hamites, and many other shells belonging to the chalk, mixt with numerous remains of marine animals that are peculiar to itself. A nearly perfect head of this animal was discovered in 1780, and is now in the Museum at Paris. This celebrated head during many years baffled all the skill of Naturalists; some considered it to be that of a Whale, others of a Crocodile; but its true place in the animal kingdom was first suggested by Adrian Camper, and at length confirmed by Cuvier. By their investigations it is proved to have been a gigantic marine reptile, most nearly allied to the Monitor.* The geological epoch at which the Mosasaurus

* The Monitors form a genus of Lizards, frequenting marshes and the banks of rivers in hot climates; they have received this name from the prevailing, but absurd, notion that they give warning by a whistling noise, of the approach of Crocodiles and Caymans. One species, the Lacerta nilotica, which devours the eggs of Crocodiles, has been sculptured on the monuments of ancient Egypt.

[216 MARINE SAURIANS.] first appeared, seems to have been the last of the long series, during which the oolitic and cretaceous groupes were in process of' formation. In these periods the inhabitants of our planet seem to have been principally marine, and some of the largest creatures were Saurians of gigantic stature, many of them living in the sea, and controlling the excessive increase of the then existing tribes of' fishes.

From the lias upwards, to the commencement of the chalk formation, the Ichthyosauri and Plesiosauri were the tyrants of the ocean; and just at the point of' time when their existence terminated, during the deposition of the chalk, the new genus Mosasaurus appears to have been introduced, to supply for a while their place and office,* being itself destined in its turn to give place to the Cetacea of the tertiary periods. As no Saurians of the present world are inhabitants of the sea, and the most powerful living representatives of this order, viz. the Crocodiles, though living chiefly in water, have recourse to stratagem rather than speed, for the capture of their prey, it may not be unprofitable to examine the mechanical contrivances, by which a reptile, most nearly allied to the Monitor, was so constructed, as to possess the power of moving in the sea, with sufficient velocity to

* Remains of the Mosasaurus have been discovered by Mr. Mantell in the upper chalk near Lewes, and by Dr. Morton in the green sand of Virginia.

[217 MOSASAURUS.] overtake and capture such large and powerful fishes, as from the enormous size of its teeth and jaws, we may conclude it was intended to devour.

The head and teeth, (Pl. 20.) point out the near relations of this animal to the Monitors ; and the proportions maintained throughout all the other parts of the skeleton warrant the conclusion, that this monstrous Monitor of the ancient deep was five and twenty feet in length, although the longest of its modern congeners does not exceed five feet. The head here represented measures four feet in length, that of the largest Monitor does not exceed five inches. The most skilful Anatomist would be at a loss to devise a series of modifications, by which a monitor could be enlarged to the length and bulk of a Grampus,* and at the same time be fitted to move with strength and rapidity through the waters of the sea; yet in the fossil before us, we shall find the genuine characters of a Monitor maintained throughout the whole skeleton, with such deviations only as tended to fit the animal for its marine existence.

The Mosasaurus had scarcely any character in common with the Crocodile, but resembled the Iguanas, in having an apparatus of teeth fixed on the pterygoid bone, (Pl. 20, k.) and placed in the roof of its mouth, as in many

* The Grampus is from 20 to 25 feet long, and very ferocious, feeding on seals and porpoises as well as on fishes.

[218 MARINE SAURIANS.] serpents and fishes, where they act as barbs to prevent the escape of their prey.*

The other parts of the skeleton follow the character indicated by the head. The vertebrue are all concave in front, and convex behind; being fitted to each other by a ball and socket joint, admitting easy and universal flexion. From the centre of the back to the extremity of the tail, they are destitute of articular apophyses, which are essential to support the back of animals that move on land: in this respect, they agree with the vertebræ of' Dolphins, and were calculated to facilitate the power of swnnining; the vertebræ of the neck allowed to that part also more flexibility than in the Crocodiles.

The tail was flattened on each side, but high and deep in the vertical direction, like the tail of a Crocodile; forming a straight oar of immense strength to propel the body by horizontal

* The teeth have no true roots and are not hollow, as in the Crocodiles, but when full grown, are entirely solid, and united to the sockets by a broad and firm base of bone, formed from the ossification of' the pulpy matter which had secreted the tooth, and still further attached to the jaw by the ossification of the capsule that had furnished the enamel. This indurated capsule, passed like a circular buttress around its base, tending to make the tooth an instrument of prodigious strength. The young tooth first appeared in a separate cell in the bone of the jaw, (Pl. 20, h.) and moved irregularly across its substance, until it pressed against the base of the old tooth; causing it gradually to become detached, together with its base by a kind of necrosis, and to fall off like the horns of a Deer. The teeth, in the roof of the mouth, are also constructed on the same principle with those in the jaw, and renewed in like manner.

[219 MOSASAURUS.] movements, analogous to those of skulling. Although the number of caudal vertebræ was nearly the same as in the Monitor, the proportionate length of the tail was much diminished by the comparative shortness of the body of each vertebra; the effect of this variation being to give strength to a shorter tail as an organ for swimming; and a rapidity of movement, which would have been unattainable by the long and slender tail of the Monitor, which assists that animal in climbing. There is a further provision to give strength to the tail, by the chevron bones being soldered firmly to the body of each vertebra, as in fishes.

The total number of vertebrae was one hundred and thirty-three, nearly the same as in the Monitors, and more than double the number of those in the Crocodiles. The ribs had a single head, and were round, as in the family of Lizards. Of the extremities, sufficient fragments have been found to prove that the Mosasaurus, instead of legs, had four large paddles, resembling those of the Plesiosaurus and the Whale: one great use of these was probably to assist in raising the animal to the surface, in order to breathe, as it apparently had not the horizontal tail, by means of which the Cetacea ascend for this purpose. All these characters unite to show that t.he Mosasaurus was adapted to live entirely in the water, and that although it was of such vast proportions conipared with

[220 MARINE SAURIANS.] the living genera of these families, it formed a link intermediate between the Monitors and the Iguanas. However strange it may appeal to find its dimensions so much exceeding those of any existing Lizards, or to find marine genera in the order of Saurians, in which there exists at this time no species capable of living in the sea; it is scarcely less strange than the analogous deviations in the Megalosaurus and Iguanodon, which afford examples of still greater expansion of the type of the Monitor and Iguana, into colossal forms adapted to move upon the land Throughout all these variations of proportion, we trace the persistence of the same laws, which regulate the formation of living genera, and from the combinations of perfect mechanism that have, in all times, resulted from their operation, we infer the perfection of the wisdom by which all this mechanism was designed, and the immensity of the power by which it has ever been upheld.

Cuvier asserts of the Mosasaurus that before he had seen a single vertebra, or a bone of any of its extremities, he was enabled to announce the character of the entire skeleton, from the examination of the jaws and teeth alone, and even from a single tooth. The power of doing this results from those magnificent laws of co-existence, which form the basis of the science of comparative anatomy, and which give the highest interest to its discoveries.

[221 PTERODACTYLE.]

AMONG the most remarkable disclosures made by the researches of Geology, we may rank the flying reptiles, which have been ranged by Cuvier under the genus Pterodactyle; a genus presenting more singular combinations of form, than we find in any other creatures yet discovered amid the ruins of the ancient earth.

The structure of these animals is so exceedingly anomalous, that the first discovered Pterodactyle (Pl. 21) was considered by one naturalist to be a bird, by another as a species of bat, and by a third as a flying reptile.

This extraordinary discordance of opinion respecting a creature whose skeleton was almost entire, arose from the presence of characters apparently belonging to each of the three classes to which it was referred. The form of its head, and length of neck, resembling that of birds, its wings approaching to the proportion and form of

* See Pl. 1, Figs. 42, 43, and Plates 21, 22.

Pterodactyles have hitherto been found chiefly in the quarries of lithographic limestone of the jura formation at Aichstadt and Solenhofen; a stone abounding in marine remains, and also containing Libellulæ, and other insects. They have also been discovered in the lias at Lyme Regis, and in the oolitic slate of Stonesfield.

[222 FLYING SAURIANS.] those of bats, and the body and tail approximating to those of ordinary Mammalia. These characters, connected with a small skull, as is usual among reptiles, and a beak furnished with not less than sixty pointed teeth, presented a combination of apparent anomalies which it was reserved for the genius of Cuvier to reconcile. In his hands, this apparently monstrous production of the ancient world, has been converted into one of the most beautiful examples yet afforded by comparative anatomy, of the harmony that pervades all nature, in the adaptation of tIme same parts of the animal frame, to infinitely varied conditions of existence.

In the case of the Pterodactyle we have an extinct genus of the Order Saurians, in the class of Reptiles, (a class that now moves only on land or in the water), adapted by a peculiarity of structure to fly in the air. It will be interesting to see how the anterior extremity, which in the fore leg of the modern Lizard and Crocodiles is an organ of locomotion on land, became converted into a membraniferous wing; and how far the other parts of the body are modified so as to fit the entire animal machine for the functions of flight. The details of this enquiry will afford such striking examples of numerical agreement in the component bones of every limb,with those in the corresponding limbs of living Lizards, and are at the same time so illustrative of contrivances for the adjustment of the same

[223 PTERODACTYLE.] organ to effect different ends, that I shall select for examination a few points, from the long and beautiful analysis which Cuvier has given of the structure of this animal.

The Pterodactyles are ranked by Cuvier among the most extraordinary of all the extinct animals that have come under his consideration; and such as, if we saw them restored to life, would appear most strange, and most unlike to any thing that exists in the present world. — "Ce sont incontestablement de tous les êtres dont ce livre nous révele l'ancienne existence, les plus extraordinaires, et ceux qui, si on les voyait vivans, paroîtroient les plus étrangers à toute Ia nature actuelle." (Cuv. Oss. Foss. Vol.V. Pt. II, p. 379.)

We are already acquainted with eight species of this genus, varying from the size of a Snipe to that of a Cormorant.*

In external form, these animals somewhat resemble our modern Bats and Vampires: most of them had the nose elongated, like the snout of a Crocodile, and armed with conical

In Pl. 21, I have given an engraving of' the Pterodactylus longirostris, which was first published by Collini, and formed the basis on which this genus was established.

At Pl. 22, O. is engraved the smallest known species, P. Brevirostris, from Solenhofen, described by Professor Soemmering.

A figure and description of a third species, P. macronyx, from the lias at Lyme Regis, have been published by myself, (Geol. Trans. Lond. second series, Vol. 3, pt. 1). This species was about the size of a Raven, and its wings, when expanded, must

[224 FLYING SAURIANS.] teeth. Their eyes were of enormous size, apparently enabling them to fly by night. From their wings projected fingers, terminated by long hooks, like the curved claw on the thumb of the Bat. These must have formed a powerful paw, wherewith the animal was enabled to creep or climb, or suspend itself from trees.

It is probable also that the Pterodactyles had the power of swimming, which is so common in reptiles, and which is now possessed by the Pteropus Pselaphon, or Vampire Bat of the island of Bonin. (See Zool. Journ. No. 16, p. 458.) " Thus, like Milton's fiend, all qualified for all services and all elements, the creature was a fit companion for the kindred reptiles that swarmed in the seas, or crawled on the shores of a turbulent planet.

"The Fiend,
O'er bog, or steep, through strait, rough, dense, or rare,
With head, hands, wings, or feet, pursues his way,
And swims, or sinks, or wades, or creeps, or flies."

Paradise Lost, Book II. line 947.

have been about four feet from tip to tip. A fourth species, P. crassirostris, has been described by Professor Goldfuss. In Pl. 22, N. 1 have given a reduced copy of his plate of the specimen; and in Pl. 22, A. a copy of his restoration of the entire animal. Count Munster has described another species, P. medius. Cuvier describes some bones of a species, P. grandis, four times as large as P. longirostris, which latter was about the size of a Wood cock. Professor Goldfuss has described a seventh species from Solenhofen, P. Munsteri; and has proposed the name P. Bucklandi, for the eighth undescribed species found at Stonesfield.

[225 PTERODACTYLE.] air, and shoals of no less monstrous Ichthyosauri and Plesiosauri swarming in the ocean, and gigantic Crocodiles, and Tortoises crawling on the shores of the primæval lakes and rivers, air, sea, and land must have been strangely tenanted in these early periods of our infant world." *

As the most obvious feature of these fossil reptiles is the presence of organs of flight, it is natural to look for the peculiarities of the Bird or Bat, in the structure of their component bones. All attempts, however, to identify them with Birds are stopped at once by the fact of their having teeth in the beak, resembling those of reptiles: the form of a single bone, the os quadratum, enabled Cuvier to pronounce at once that the creature was a Lizard: but a Lizard possessing wings exists not in the present creation, and is to be found only among the Dragons of romance and heraldry; while a moment's comparison of the head and teeth

* Geol. Trans. Lond. N. S. Vol. III, part l.

One diminutive living species of Lizard, (the Draco volans, see Pl. 22, L.) differs from all other Saurians, in having an appearance of imperfect wings, produced by a membranous expansion of the skin over the false ribs which project almost horizontally from the back; the membrane expanded by these false ribs, acts like a parachute to support the animal in leaping from tree to tree, but has no power to beat the air, or become an instrument of true flight, like the arm or wing of Birds and Bats; the arm or foreleg of the Draco volans differs not from that of common Lizards.

[226 FLYING SAURIANS.] with those of Bats (Pl. 21, and Pl. 22, M.) shows that the fossil animals in question cannot be referred to that family of flying Mammalia.

The vertebrae of the neck are much elongated, and are six or seven only in number, whereas they vary from nine to twenty-three in birds.* In birds the vertebrae of the back also vary from seven to eleven, whilst in the Pterodactyles there are nearly twenty; the ribs of the Pterodactyles are thin and thread-shaped, like those of Lizards, those of birds are flat and broad, with a still broader recurrent apophysis, peculiar to them. In the foot of birds, the metatarsal bones are consolidated into one: in the Pterodactyles all the metatarsal bones are distinct; the bones of the pelvis also differ widely from those of a bird, and resemble those of a Lizard;

* In one species of Pterodactyle, viz, the P. macronyx, Geol. Trans. N. S. V. iii. p1. 27, page 220, from the lias at Lyrne Regis, there is an unusual provision for giving support and movement to a large head at the extremity of a long neck, by the occurrence of bony tendons running parallel to the cervical vertebra, like the tendons that pass along the back of the Pigmy Musk (Moschus pygmæus,) and of many birds. This provision does not occur in any modern Lizards, whose necks are short, and require no such aid to support the head. In the compensation which these tendons afforded for the weakness arising from the elongation of the neck, we have an example of the same mechanism in an extinct order of the most ancient reptiles, which is still applied to strengthen other parts of the vertebral column, in a few existing species of rnammahia and birds.

[227 PTERODACTYLE.] all these points of agreement, with the type of Lizards, and of difference from the character of birds, leave no doubt as to the place in which the Pterodactyles must be ranged, among the Lizards, notwithstanding the approximation which the possession of wings seems to give them to Birds or Bats.

The number and proportions of the bones in the fingers and toes in the Pterodactyle, require to be examined in some detail, as they afford coincidences with the bones in the corresponding parts of Lizards, from which important conclusions may be derived.

As an insulated fact, it may seem to be of little moment, whether a living Lizard or a fossil Pterodactyle, might have four or five joints in its fourth finger, or its fourth toe; but those who have patience to examine the minutiae of this structure, will find in it an exemplification of the general principle, that things apparently minute and trifling in themselves, may acquire importance, when viewed in connexion with others, which, taken singly, appear equally insignificant. Minutiae of this kind, viewed in their conjoint relations to the parts and proportions of other animals, may illustrate points of high importance in physiology, and thereby become connected with the still higher considerations of natural theology. If we examine the fore-foot of the existing Lizards, (Pl. 22, B.) we

[228 FLYING SAURTANS.} find the number of joints regularly increased by the addition of one, as we proceed from the first finger, or thumb, which has two joints, to the third, in which there are four; this is precisely the numerical arrangement which takes place in the three first fingers of the hand of the Pterodactyle; (Pl. 22, C. D. E. N. O. Figs. 30-38.) thus far the three first fingers of the fossil reptile agree in structure with those of the fore foot of living Lizards; but as the hand of the Pterodactyle was to be converted into an organ of flight, the joints of the fourth, or fifth finger were lengthened, to become expansors of a membranous wing.*

* Thus in the P. Longirostris (Pl. 21, 39-42.) and P. Brevirostris, (Pl. 22, Fig. O, 39-42,) the fourth finger is stated by Cuvier to have four elongated joints, and the fifth or ungual joint to be omitted, as its presence is unnecessary. In the P. Crassirostris, according to Goldfuss (Pl. 22, Figs. A, N,) this claw is present upon the fourth finger, (43) which thus has five bones, and the fifth finger is elongated to carry the wing. Throughout all these arrangements in the fore-foot, the normal numbers of the type of Lizards are maintained.

If, as appears from the specimen engraved by Goldfuss, of P. Crassirostris, (Pl. 22, N, 44, 45,) the fifth finger was elongated to expand the wing, we should infer from the normal number of joints in the fifth finger of Lizards being only three, that this wing finger had but three joints. In the fossil itself the two first joints only are preserved, so that his conjectural addition of a fourth joint to the fifth finger, in the restored figure, (Pl. 22, A, 47,) seems inconsistent with the analogies, that pervade the structure of this, and of every other species of Pterodactyle, as described by Cuvier.

[229 PTERODACTYLE.] As the bones in the wing of the Pterodactyle thus agree in number and proportion with those in the fore-foot of the Lizard, so do they differ entirely from the arrangement of the bones which form the expansors of the wing of the Bat.*

The total number of toes in the Pterodactyles is usually four; the exterior, or little toe, being deficient; if we compare the number and proportion of the joints in these four toes with those of Lizards, (Pl. 22, F, G, H, I,) we find the agreement as to number, to be not less perfect than it is in the fingers; we have, in each case, two joints in the first, or great toe, three in the second, four in the third, and five in the fourth. As to proportion also, the penultimate joint is always the longest, and the antepenultimate, or last but two, the shortest; these relative proportions are also precisely the same, as in the feet of Lizards. The apparent use of this disposition

* The Bat, see Pl. 22, M, 30, 31, the first finger or thumb alone, is free, and applied to the purpose of suspension and creeping; the expansors of the wing are formed by the metacarpal bones, (26-29,) much elongated and terminated by the minute phalanges of the other four fingers, 32-45, thus presenting an adaptation of the hand of the mammalia to the purposes of flight, analogous to that which in the fossil world, the Pteroclactyle affords with respect to the hand of Lizards.

According to Goldfuss the P. Crassirostris had one more toe than Cuvier assigns to the other species of Pterodactyles ; in this respect it. is so far from violating the analogies

[230 FLYING SAURIANS.} of the shortest joints in the middle of the toes of Lizards, is to give greater power of flexion for bending round, and laying fast hold on twigs and branches of trees of various dimensions, or on inequalities of the surface of the ground or rocks, in the act of climbing, or running.*

All these coincidences of number and proportion, can only have originated in a premeditated adaptation of each part to its peculiar office; they teach us to arrange an extinct animal under an existing family of reptiles; and when we find so many other peculiarities of this tribe in almost every bone of the skeleton of the Pterodactyle, with such modifications, and such only as were necessary to fit it for the purposes of flight, we perceive unity of design pervading every part, and adapting to motion in the air, organs which in other genera

we are considering, that it adds another approximation to the character of the living Lizards; we have seen that it also differs from the other Pterodactyles, in having the fifth, instead of the fourth finger elongated, to become the expansor of the wing.

It is however probable that the fifth toe had only three joints, for the same reasons that are assigned respecting the number of joints in the fifth finger. In the P. Longirostris, Cuvier considers the small bone, (Pl. 21, 5, 6,) to be a rudimentary form of the fifth toe.

* A similar numerical disposition prevails also in the toes of birds, attended by similar advantages.

[231 PTERODACTYLE.] are calculated for progression on the ground, or in the water.

If we compare the foot of the Pterodactyle with that of the Bat, (see Pl. 22, K,) we shall find that the Bat, like most other mammalia, has three joints in every toe, excepting the first, which has only two; still these two, in the Bat, are equal in length to the three bones of the other toes, so that the five claws of its foot range in one strait line, forming altogether the compound hook, by which the animal suspends itself in caves, with its head downwards, during its long periods of hybernation; the weight of its body being, by this contrivance, equally divided between each of the ten toes. The unequal length of the toes of the Pterodactyle must have rendered it almost impossible for its claws to range uniformly in line, like those of the Bat, and as no single claw could have supported for a long time the weight of the whole body, we may infer that the Pterodactyles did not suspend themselves after the manner of the Bats. The size and form of the foot, and also of the leg and thigh, show that they had the power of standing firmly on the ground, where, with their wings folded, they possibly moved after the manner of birds; they could also perch on trees, and climb on rocks and cliffs, with their hind and fore feet conjointly, like Bats and Lizards.

[232 FLYING SAURIANS.] With regard to their food, it has been conjectured by Cuvier, that they fed on insects, and from the magnitude of their eyes that they may also have been noctivagous. The presence of large fossil Libellulæ, or Dragon-flies, and many other insects, in the same lithographic quarries with the Pterodactyles at Solenhofen, and of the wings of coleopterous insects, mixed with bones of Pterodactyles, in the oolitic slate of Stonesfield, near Oxford, proves that large insects existed at the same time with them, and may have contributed to their supply of food. We know that many of the smaller Lizards of existing species are insectivorous; some are also carnivorous, and others omnivorous, but the head and teeth of two species of Pterodactyle, are so much larger and stronger than is necessary for the capture of insects, that the larger species of them may possibly have fed on fishes, darting upon them from the air after the manner of Sea Swallows and Solan Geese. The enormous size and strength of the head and teeth of the P. Crassirostris, would not only have enabled it to catch fish, but also to kill and devour the few small marsupial mammalia which then existed upon the land.

The entire range of ancient anatomy, affords few more striking examples of the uniformity of the laws, which connect the extinct animals of the fossil creation with existing organized beings,

[233 PTERODACTYLE.]  than those we have been examining in the case of the Pterodactyle. We find the details of parts which, from their minuteness should seem insignificant, acquiring great importance in such an investigation as we are now conducting; they show not less distinctly, than the colossal limbs of the most gigantic quadrupeds, a numerical coincidence, and a concurrence of proportions, which it seems impossible to refer to the effect of accident; and which point out unity of purpose, and deliberate design, in some intelligent First Cause, from which they were all derived. We have seen that whilst all the laws of existing organization in the order of Lizards, are rigidly maintained in the Pterodactyles; still, as Lizards modified to move like birds and Bats in the air, they received, in each part of their frame, a perfect adaptation to their state. We have dwelt more at length on the minutiae of their mechanism, because they convey us back into ages so exceedingly remote, and show that even in those distant eras, the same care of a common Creator, which we witness in the mechanism of our own bodies, and those of the myriads of inferior creatures that move around us, was extended to the structure of creatures, that at first sight seem made up only of monstrosities.