PLATE 5. 



Figure 24 from gold-choride preparation; all others from Golgi preparations. 



Figure 22. Branchiostoma caribaeum. Transverse section. Nerve fibers 

 entering a dorsal root, in the middle region of the animal. 

 X 238. 



Figure 23. B. caribaeum. Anterior at the left (?) . A frontal section. Nerves 

 in the transverse muscles, toward the anterior end of the body, 

 on the right side. X 238. 



Figure 24. B. caribaeum. A view of the inner surface of skin stripped from 

 the dorsal fin in the region of the 20th myomere from the 

 posterior end of the animal, showing fibers and other struc- 

 tures in connection with a branch of the dorsal ramus of a 

 dorsal nerve. Ordinary epithelial cells are outlined at e. 

 Special cells in the epithelial layer are marked g, and certain 

 cell-like structures in connection with fibers are shown at c, c. 

 A star-like place of union of fibers is indicated at s. The 

 bases of the epithelial cells lie just exterior to the fibers drawn. 

 X410. 



Figure 25. B. lanceolatum. Dorsal aspect of frontal section through the 

 7th myomere of the right side showing a portion of the corre- 

 sponding ventral nerve root. X 203. 



Figure 26. B. lanceolatum. Dorsal aspect of frontal section, next ventral 

 to the preceding one, showing a more ventral portion of the 

 same nerve. X 203. 



Figure 27. B. lanceolatum. Frontal section at the level of the dorsal 

 margin of the notochord, directlj' ventral to the neural tube. 

 The myomere of the figure is slightly posterior to the middle 

 of the specimen, on the right side. Smooth motor fibers are 

 shown, and a closely associated group of end-plates situated 

 in the side muscles, near the posterior myoseptum. X 141. 



Figure 28. B. lanceolatum. Frontal section through the middle of the 

 notochord, showing long motor fibers and end-plates in the 

 side muscles. The.se muscles are posterior to the middle 

 region of the body. X 141. 



Figure 29. B. lanceolatum. Dorsal aspect of frontal section, showing 

 motor fibers in the side muscles of the 18th myomere of the 

 right side, in the region of the neural tube just ventral to the 

 place of exit of the dorsal nerve roots. The section is about 

 46 micra in thickness. X 99. 



Figure 30. Branchiostoma caribaeum. A nerve cell in the ventral part of 

 the pharynx, in connection with the nerve plexus of that 

 region. The cell lies on the exterior of an endostylar plate. 

 X 226. 



