Peentiss. — Otocyst Crustacea. 



PLATE 4. 



Figures 13-18 are of Palcemonetes. Figures 19-22 are of lobster larvce. In Figures 

 19-21 dorsal side is up and the lateral side is at the right ; in Figure 22 anterior 

 is at the riglit, dorsal side up. 



Fig. 13. Portion of inner flagellum of first antenna, showing olfactory hairs and 



their peripheral ganglionic masses. Metiiylen blue. X 125. 

 Fig. 14. Gustatory hairs and nerve elements from the basipod of second maxilla. 



Methylen blue. X 95. 

 Fig. 15. Fibrillations in peripheral otic nerve fibre. Methylen blue. X 1300. 

 Fig. 16. Ganglion cell of otocyst and peripheral nerve process surrounded by 



myelin sheath. X 600. 

 Fig. 17. Ganglion cell of otocyst, and sheath nucleus. X 1300. 

 Fig. 18. Ganglion cell of otocyst. Methylen blue. X 770. 



Fig. 19. Transverse section through right antennule of first lobster larva. X 168. 

 Fig. 20. Transverse section through right antennule of second lobster larva ; 



beginning of invagination. X 168. 

 Fig. 21. Transverse section through right antennule of third lobster larva. 



X 168. 

 Fig. 22. Parasagittal section through antennule of second lobster larva. X 168. 



