^2 Journal of Comparative Neurology. 



the ventral and ventro-lateral surfaces of the cord. Behind 

 (caudad of) the roots the nerve cells entirely surround the gan- 

 glia and occupy the mesal plane as well. 



Within the ventral chain, beneath the origin of the thor- 

 acic nerves, there is a pair of ellipsoidal cavities. These might 

 properly be called thoracic ventricles. 



Second Maxillary Nerves. — This nerve arises from the lat- 

 eral aspect of the first ganglion behind (caudad of) the sub- 

 oesophageal ganglion. 



Leg Nerves. — From the last ventral ganglion of Cypris 

 arise two paired nerves and one unpaired nerve. The paired 

 nerves innervate the legs, while the unpaired nerve passes into 

 the abdomen. The nerve of the first leg passes immediately 

 latero-ventrad to the first leg ; but the nerve of the second leg 

 passes backwards (caudad) along with the abdominal nerve, a 

 short distance before passing to the second leg [fig. 42]. 



Abdominal Nerve. — As has been stated, from the caudal 

 portion of the last ventral ganglion a large unpaired median 

 nerve passes upwards and backward (dorso-caudad) into the ab- 

 domen. This is the abdominal nerve. After entering the ab- 

 domen, this nerve becomes more and more attenuated, owing 

 to the fact that it gives off fibres to the reproductive system 

 [fig. 32 an, 42 Ab\ 



The above descriptions of the principal nerves of Cypris do 

 not agree either with the descriptions of the few men who have 

 written on this subjects or with the statements made in my pre- 

 liminary paper. I cannot answer for the other men, but my 

 error was in mistaking the labial nerve for the mandibular nerve. 

 If you but recall the compactness of the anterior (cephalic) re- 

 gion of the body of Cypris, you can see how easy it would be 

 to make such a mistake. However, I now have at hand sev- 

 eral series which demonstrate, beyond the shadow of a doubt, 

 that the nerves arise as stated in this paper. 



No doubt it is this same compactness of the cephalic por- 

 tion of the body of Cypris which is responsible for the non-dis- 

 covery of the labial, labral, and thoracic nerves by other 

 observers. 



