PLATE 7. 



Figures 37-39 and 41 from methylene-blue preparations; figure 40 from 

 Golgi, and figure 42 from gold-chloride (after Ranvier) preparations. 



Figure 37. Branchiostoma lanceolatum. The exteriorly directed cutaneous 

 branchlets of left dorsal nerve XVI. The epithelium is not 

 present. X 41. 



Figure 38. B. lanceolatum. Cutaneous plexuses distributed over the side 

 muscles, formed from connecting branches of left nerves XI, 

 and XII. The coarser plexus is marked pi, and the finer, 

 more superficial plexus, pi. A visceral nerve branch is indi- 

 cated at a. X 84. 



Figure 39. B. caribaeum. Cutaneous plexuses between left dorsal nerves 

 XXXV, XXXVI and XXXVII, in the region of the side 

 muscles. The letters correspond to those in preceding 

 figure. X 17.5. 



Figure 40. B. lanceolatum. Anterior is up. Frontal section. Nerve 

 fibers entering the root of right dorsal nerve XXI. X 238. 



Figure 41. B. lanceolatum. Dorsal is at the left. A plexus formed by the 

 breaking up, for a short distance, of the main stem of the 

 ventral ramus of right dorsal nerve XXVII. X 84. 



Figure 42. B. caribaeum. A view of the outer surface of skin taken from 

 the region over the side muscles, near the dorsal fin. Special 

 cells are indicated at g, and modified cells at s. Apparent 

 exudations from the special cells are marked e. The exuda- 

 tions lie at higher focus in their distal portions. X 1050. 



