26 Journal of Comparative Neurology. 



ventro-meso-caudad to the median unpaired Vagina, which lies 

 on the ventral side near the abdominal rami. The walls of the 

 abdominal portions of the sexual ducts are quite glandular. 

 They secrete the chorion of the egg. 



Near the ventral side of the body there is a broad chitin- 

 ous exoskeleton [fig. 1,5], to which the muscles of the extrem- 

 ities are attached. 



Surrounding all the organs of the body (nervous system 

 included) we find a mesenchyme-like connective tissue. This 

 connective tissue consists of membranous and fibrous cells, 

 among which are scattered larger and denser irregularly shaped 

 cells [fig. 1, 1 1]. 



It is important that no one should suppose that the above 

 description is intended as an exhaustive histological study of 

 the Ostracoda. Although it contains some points that have not 

 yet been brought out by other investigators, nevertheless, it is 

 given merely to facilitate an intelligent description of the ner- 

 vous system and its relation to the extra-neural systems. 



The Central Nervous System. 



The central nervous system of Cypris, like that of the 

 higher Crustacea {Malacostraca) is composed of a supra-oesoph- 

 ageal ganglion which is united by a pharyngeal collar to a multi- 

 ganglionic ventral chain. This is true, not only of Cypris, but 

 also of Cjpridopsis, Cyclocypris and Candona. When we recall 

 that Dr. Lang states that in Cythcre and Halocypris this is also 

 the case, we have grounds for believing that in all Ostracoda the 

 central nervous system consists of a supra-oesophageal ganglion 

 which is united to a ventral chain by a pharyngeal collar. 



Snpra-oesophagcal ganglion. — This ganglion lies about half 

 way between the dorsal and ventral surfaces of the body and be- 

 tween the oesophagus and the cephalic border of the body. It 

 lies just below the place where the oesophagus enters the mid- 

 gut. In my preliminary paper the statement was made that 

 this ganglion was much nearer to the dorsal than to the ventral 

 surface. This was a misprint ; the ganglion usually lies nearer 

 the ventral than the dorsal surface. This is a compound gan- 



