154 Journal of Comparative Neurology. 



homologous with a sensory root, while the ganglion lies upon 

 the skin in immediate vicinity to its point of origin The dorsal 

 ramus gives off a N. cutaneus dorsalis and a N. lateralis dor- 

 salis and the ventral ramus forms a N. cutaneus ventralis and 

 also a N. visceralis. The ventral root is the special nerve of 

 the body muscles. 



The mouth in \mphioxus is not produced from a gill cleft ; 

 one such cleft (ciliated sac) lies in front and another (pseudo- 

 branchium) behmd, forming 14 in all. The first cleft lies on 

 the caudal margin of the first metamer and all are inter seg- 

 mental. 



From a study of Aminocetes, the author concludes that none 

 of the postoral myomers disappear (contra K-Uj)ffer.) 



The rectus externus corresponds to a prootic myomer. 

 The obliquus superior is a branch of the pharyngeal velum 

 (corresponding to the abductor of the mandiblar arch.) The 

 other eye muscles were not satisfactorily construed but are prob- 

 ably derived from the constrictors of the visceral apparatus. 



The trigeminus corresponds to two nerves and contains (i). 

 the frontalis primum (lateralis dorsalis); (2), portio profunda of 

 ophthalamicus (lateralis dorsalis); (3), mandibularis (ramus ven- 

 tralis.) 



The maxillary undoubtedly corresponds to a R. ventralis 

 and belongs to "trigeminus .\," while the mandibularis corres- 

 ponds to the ventral ramus of " trigeminus B." 



The ramus ventralis, which springs from the caudal portio i 

 of the facial ganglion, is the nerve of the pseudo branchial 

 groove and the hyomandibularis is its posttrematic branch, while 

 a branch corresponding to a pretrematic gives off a branch to 

 Kupffer's organ. 



The acusticus is a N. lateralis dorsalis and the inner ear cor- 

 responds to an organ of the lateral line. 



A primary vagus, supplying a single segment is distinguished 

 from five ventral ganglia of succeeding segments. 



The oculomotor is a derivative of the visceral rami of the 

 trigeminus A and the trochlearis of trigeminus B. The abdu- 

 cens is the first ventral root belonging to the facial. In the 

 main, therefore, Hatschek agrees with Gegenbaur. 



