232 Journal of Comparative Neurology. 



The r. spinosus c {r. sp. c.) is perfectly typical. It 

 runs back over the cranium and first free vertebra and 

 effects the anastomosis with the r. communicans of the 

 second spinal and the r. lateralis accessorius in the septum 

 laterally of the interspinal muscles in the usual manner. 

 It is composed of motor fibres, and just as it leaves the 

 ganglion it gives off a motor branch dorsally for the dorsal 

 musculature. 



The r. inedius c {r. ni. c.) arises just cephalad of the r. 

 spinosus. It is a small nerve and, like the corresponding 

 nerve of b, it contains chiefly motor, with a few sensory 

 fibres. It runs for a considerable distance cephalad in 

 the ganglion, which it leaves close behind the r. medius b. 

 It follows the latter nerve, lying ventrally of it, for some 

 distance, though there is no anastomosis between them. 

 It, however, goes much farther caudad than that nerve, 

 running for a time parallel to the first intermuscular bone, 

 and at the level of the third branch of the r. lateralis vagi 

 (765) it crosses the second twig of that nerve (r. /. 2) and 

 anastomoses with it. Some of its sensory fibres apparently 

 go out to the skin with that twig, others independently a 

 little farther caudad, the motor fibres having already been 

 given off. Thus it appears that the r. medius of both b 

 and c conforms to the typical arrangement of the spinal 

 nerves in that the sensory fibres are distributed to the 

 skin about the lateral line. 



The ventral ramus of c takes the remaining fibres from 

 the ventral root c and a smaller number of sensory fibres. 

 It is smaller than that of b. It follows the latter nerve 

 out under the dorsal musculature and soon joins it, the 

 mixed trunk soon thereafter being joined by the r. ven- 

 tralis of the second spinal nerve. At the point of union 

 with the latter nerve a small motor twig (derived, it is 



