PLATE 2. 



All figures are from methylene-blue preparations. 



Figure 5. Branchiostoma caribaeum. Nerves of the right side of the ros- 

 trum. The epithelium of the skin is not present. Numerous 

 cells of Quatrefages, Q, Q, are shown. X 92. 



Figure 6. B. caribaeum. Anterior dorsal portion of a transparent specimen, 

 showing the exit of the anterior dorsal nerves from the neural 

 tube on the right side of the body. The branches of the dorsal 

 rami of these nerves are drawn. Nerve II shows two roots. 

 The places of division of these nerves into dorsal and ventral 

 rami are also shown. X 32. 



Figure 7. B. caribaeum. The main branches of the dorsal nerves of the 

 buccal region, on the left side of the body. The branches r, ;•, 

 pass to the right side of the body; c, a, indicate places of 

 anastomosis. The branches o, o, form part of the outer mouth 

 plexus; those marked i, i, form part of the inner mouth plexus; 

 V. band nerve of velum. X 34. 



Figure 8. B. lanceolatum. Anterior is up. The innervation of the velum. 

 The epithelium of the velum is not present. The velar tenta- 

 cles are indicated by /\ t-; a. a, point where one velar nerve 

 band was cut; b, fe, similar point in another cut nerve band; 

 b', the cut nerve b near the point where it diverges from 5. 

 For nerves a, /?, 7, 5 see text p. 590. X 41. 



Figure 9. B. lanceolatum. Anterior is up. A portion of the velar plexus, 

 and the nerves of two velar tentacles; c, c, cells in the epithelial 

 covering remaining attached to the nerves. Cells, or nuclei, 

 in connection with the velar plexus are shown at )i. n. X 123. 



Figure 10. B. lanceolatum. A portion of the fine plexus of a gonadial 

 pouch. X 343. 



