Fig. 1 and 2. Copied in part from the restoration of the Bradford, or Pear Encrinite (Apiocrinites rotundus) in Miller's Crinoidea, Pag. 19. Pl. l. In Fig. l. the arms are expanded, and in Fig. 2. nearly closed.

* Much value is added to this and the following Plates, relating to Crinoidea, by their having been engraved (except Pl. 48.) by a Naturalist so conversant with the subjects, as Mr. Tames Sowerby.

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The length of the jointed flexible stems has been taken from some entire stems in the collection of Mr. Channing Pearce of Bradford, near Bath. Two young individuals are attached to the calcareous Pedicle or Base of the largest specimens. (Miller.)

Fig. 2. a. represents the remedial effect of calcareous secretions in repairing an injury of the joints of the stem. (Miller.)

Fig. 3. Pyriform Body of Apiocrinites rotundus, shewing at its upper extremity the internal disposition of the bones surrounding the cavity of the stomach. (Original.)

Fig. 4. Vertical section of another pyriform Body, shewing the cavity of the Stomach, and a series of lower cavities, or hollow lenticular spaces, between the central portions of the enlarged joints of the upper portion of the vertebral column. Miller considers these spaces as enlargements of the alimentary canal, which descends through the axis of the entire column.

The surfaces of the joints of the vertebral column are striated with rays, which articulate with corresponding rays on the adjacent Plates, and allow of flexure without risk of dislocation; locking into one another nearly in the same manner as those figured in Pl. 49. Figs. 5. 7. 9. (Original.)

Fig. 5. Restored figure of Apiocrinites, 30-Dactylus, copied from Miller's Crinoidea, Page 96, Pl. l. Fig. 2. (See V. I. p. 429. Note.)

B. Base and fibres of attachment.

D. Auxiliary side Arms*.

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Fig .6. Body ofActinocrinites 30-dactylus (Nave Encrinite of Parkinson) copied from Miller's Crinoidea, P. 98. Pl. 11. (See V. I. p. 429. Note.)
Q. Pectoral Plates.
R. Capital Plates.
X. Orifice of the Mouth, or Proboscis, capable of elongation for sucking in food.

Fig. 7. Another Body of a Nave Encrinite, drawn by Mr
J. Sowerby from a specimen in the British Museum. The same is Figured by Parkinson, in his Organic Remains, Vol. II. Pl. XVII. Fig. 3. The lateral projections are the commencement of the side arms. This specimen has been corroded with acid, and consequently has lost the superficial Corrugations and [082] Tubercles which appear on the surface of Fig. 6, (Original.)
X. Orifice of the Mouth.

* These side arms afford a beautiful example of mechanical adaptations and compensations, which are thus described by Mr. Miller [081] in his admirahle Monograph on Crinoidea, p. 97. "The mechanism of the joints of the side arms, where these insert into the column, is well worthy of notice, particularly in old specimens. In the earlier stage of their formation, the side arms being very short, and having then little weight, a less firm mode of adhesion to the column than becomes requisite at a subsequent period, being then sufficient, we do not find more than one joint lodged in a socket, or concave im pression on the column; but when increase of size renders a stronger support necessary, two or three succeeding joints of the side arms become imbedded in this socket, (for which its extension as already noticed allows room) and these joints instead of being arranged in a series branching off at right angles from the column, become oblique, their direction inclining upwards, so as to aid in bearing the additional weight. The first joint of the side arms, where thus obliquely inserted in the colnmnar socket, have that portion of their circumference which is presented towards the upper part of the column, truncated, in such a curve as may fit them to the concavity of the impression where they rest against it.

The surface of these joints, which fit into the columnar impression, is smooth, being destined for adhesion only, but the articulating surface between the contiguous joints, where motion also is to be allowed, exhibits the usual mechanism of radiated ridges and furrows. These joints are convex on the side nearest the column, and concave on that most remote."