36 Mr. C. Spence Bate on the Homologies of the Carapace 



totally differs in habit and form. The opacity of the cell pre- 

 vented me from discerning whether it has a gizzard. 



EXPLANATION OF PLATES IIL and IV. 

 Plate III. 



Fig. 1. Halacarus rhodostigma, magnified, ventral surface. 



— 2. Ibid, dorsal surface of trunk. 



— 3. Ibid, rostrum and palpi. 



— 4. Ibid, punctures of surface. 



— 5. Ibid, ungues of foot. 



— 6. H. ctenopus, magnified, dorsal surface. 



— 7. Ibid, ventral surface. 



— 8. Ibid, rostrum and palpi. 



— 9. Ibid, right palpus. 



— 10. Ibid, one unguis of a foot. 



— 11. Cyamus Thf^mpsoni, magnified, ventral surface. 



— 12. Phoxichilidium olivaceum, nat. size. 



— 13. Ibid, fore-parts magnified. 



Plate IV. 



Fig. 14. Syllis longiseta, in its tube, nat. size. 



— 15. Ibid, magnified. 



— 16. Ibid, head, somewhat laterally. 



— 17. Ibid, a right foot seen from behind. 



— 18,19. Ibid, setae of the upper pencil. 



— 20. Ibid, a middle segment, from above. 



— 21. Ibid, the same, from below. 



— 22. Othonia Fabricii, magnified. 



— 23. O. Bairdii, magnified. 



— 24. Ibid, a pencil of setae, more enlarged. 



— 25. O. Johnstoni, nat. size. 



— 26. Ibid, magnified (middle segments omitted). 



— 27. Ibid, bristles of two forms. 



— 28. Ibid, a portion from a stem of the gills, with two pinnae. 



— 29. Nolella stipata, magnified. 



IV. — On the Homologies of the Carapace and on the Structure and 

 Function of the Antennce in Crustacea. By C. Spence Bate, 

 F.L.S. &c.* 



[With two Plates.] 



In the class Crustacea the most anterior articulation is that 

 which supports the eyes. This is shown most conspicuously in 

 the genus Squilla, in which animal it is united by a free joint 

 with the next succeeding; but if this lucid example were want- 

 ing, the relative position of the ophthalmic ring in advance of 

 any of the rest is clearly manifest in the larva and pupa stages 

 of the Decapoda. 



Dissection moreover leads to the same conclusion. Upon 



* Communicated by the author, having been read at the Linnaean Society, 

 April 17, 1855. 



