[071]

Fig. l. Limulus Americanus (Leach), a young specimen from Honduras, one third of nat. size. b'. Right compound Eye magnified. b''. Two single [072]

* The following letters are applied in Pl. 45 and Pl. 46, to corresponding parts of different animals. a. the shield; a'. lateral portion of the shield ; b. the eye ; b'. eye magnified ; b". frontal eyes; c. the back; d. the tail; e. branchiæ.

Eyes in front of the shield. See V. I. p. 393. (Original.)

Fig. 2. View of the under surface of Fig. 1 , shewing the crustaceous legs beneath the shield (a), and the swimming feet, bearing the Branchiæ (e), beneath the body (c). Scale, one seventh of nat. size.

Fig 2. e'. Swimming feet, (see Fig. 2 e,) enlarged to the scale of Fig. l.

Fig. 2. e". Posterior surface of one of the swimming feet, bearing the fibres of the Branchiæ. (Original.)

Fig. 3. Front view of magnified figure of Branchipus stagnalis. 3. b. The left eye mounted on a peduncle. 3. b'. The right eye still more magnified. (Original.)

Fig. 4. Side view of Branchipus stagnalis, nat. size.

Fig. 5. Magnified view of the back of Branchipus stagnalis. See V. l. p. 394. (Original.)

Fig. 6. View of the back of a Serolis from Senegal, given by M. Dufresne to Dr. Leach. See V. I. p. 392. (Original.)

Fig 7. View of the under surface of Fig. 6, shewing the union of crustaceous legs with the membranous branchiæ, e.* (Original.)

Fig. 8. Magnified view of the Branchiæ at Fig. 7,e.

Fig. 9. Back of Asaphus caudatus, from Dudley, in the collection of Mr. Stokes. (Original.)

Fig. 10. Side view of the left Eye of Fig. 9, magnified. Fig. 10'. Another Eye of Asaphus caudatus, in the collection of Mr. Bright, from the W. side of Malverli Hill. In the front of this fossil are circular depressions on the stone, from which the petrified lenses have fallen out; on each side, the lenses remain in their natural place. (Original.)

Figs. 3, 6, 6 and 7, are from original drawings by Mr. Curtis in the collection of Mr. C. Stokes.

[073]
Fig. 11. Anterior segment of the left Eye of Fig. 9, still more highly magnified, to shew the circular lenses set in their respective margins, each surrounded by six minute tubercles. (Original.)

Fig. 11'. Magnified view of a portion of the eye of Calymene macrophthalmus. (Hoeninghaus.)

Fig. 12. Under surface of the anterior portion of the shield of Asaphus platycephalus, from Lake Huron. An unique specimen, shewing at f an entrance to the stomach, analogous to that in recent Crabs. See Geol. Trans. N. S. Vol. i. Pl. 27. (Stokes.)