PLATE 8. 



All figures are from Golgi preparations, and all except 50 are from Branchi- 

 ostoma lanceolatum and are dorsal aspects of frontal sections. 



FiGUKE 43. Section (anterior at the right) through the middle of the noto- 

 chord (ch. sheath of notochord), showing part of a myomere 

 in the middle region of the animal. Long, single motor fibers 

 are drawn, the one bearing an end-plate traversing the side 

 muscles for nearly their entire width. X 14L 



Figure 44. Section (anterior at the left) through the 24th myomere of the 

 left side, showing motor fibers and an end-plate. A slight 

 impregnation of the muscle fibers adjoining the end-plate is 

 drawTi. X 203. 



Figure 45. Section showing motor end-plates in the side muscles dorsal to 

 the neural tube, on the left side. X 277. 



Figure 46. Section (anterior at the left) showing long, smooth, closely 

 associated motor fibers in the middle region of the 20th 

 myomere of the left side of the body. The section passes 

 through the notochord. X 141. 



Figure 47. Section (anterior at the right) through the region of the noto- 

 chord, showing long, smooth motor fibers near a myoseptum. 

 X 141. 



Figure 48. Section (anterior at the left) through the region of the 21st 

 myomere of the left side of the body, showing a branched 

 motor fiber near the anterior mj'oseptum. X 203. 



Figure 49. Frontal section through the region of the 19th myomere of the 

 left side, showing branched motor fibers near a myoseptum. 

 X 203. 



Figure 50. B. caribaeum. Transverse section through a ventral nerve near 

 the middle region of the body, showing a nerve fiber bearing 

 a structure (c) resembling a bipolar nerve cell. An apparent 

 nucleus is shown in the cell-like structure. X 271. 



