Turner, Nervous System of Cypris. 31 



Mandibular Nerves. — From each lateral portion of the sub- 

 oesophageal ganglion, just below ( ventro-caudad of) the place 

 of fusion of the pharyngeal collar with this ganglion, a man- 

 dibular nerve leaves the nervous chain. Just after entering the 

 mandible this nerve branches, one branch passing upwards 

 ( cephalo-dorsad ) to the mandibular muscles, while the other 

 passes downward ( cephalo-ventrad ) to a sense organ at the 

 base of the mandibular teeth [ fig. 7 iiix, 40 w/c/]. There is 

 no root ganglion to this nerve. 



Labral Netves. — From each lateral portion of the ventral 

 aspect of this same ganglion, a short distance behind (caudad 

 of) the origin of the mandibular nerve, arises a labral nerve. 

 Thence the nerve passes, in a caudally convex curve, downward 

 (ventrad) to the lower lips [fig. 32, 42 ]. The chief function 

 of this nerve is to innervate a harp-shaped sense organ located 

 in the lower lip [fig. 16 Z?]. This nerve has a root ganglion. 



First Maxillary Nerves. — A short distance caudad of the 

 origin of the mandibular nerve, a maxillary nerve leaves each 

 side of this same ganglion. This is the first maxillary nerve. 

 It passes latero-caudad to the first maxilla [fig. 7 nix''', 42]. 



TJioracic Nen'es. — All of the four pairs of nerves just de- 

 scribed arise from the ventral side of the sub-oesophageal gan- 

 glion. We now come to a pair of nerves that arise from the 

 dorsal aspect of the same ganglion. These are what I beg per- 

 mission to call the thoracic nerves. These nerves arise from 

 the lateral portion of the dorsal aspect of this ganghon just 

 back of (caudad of) the origin of the first maxillary nerve. 

 Arising as it does from the dorsal aspect of the ventral chain, 

 the root of this nerve lies immediately beneath the endoskeleton. 

 This nerve passes obliquely upwards and backwards (dorso-latero- 

 caudad), and, after branching, innervates the abductor muscles 

 of the shell [fig. 327", 42/]. 



To the best of the writer's knowlege, neither this nerve nor 

 the labial nor the labral nerves have been described by any pre- 

 vious writer on the Ostracoda. 



From the cephalic extremity of the ventral nerve chain to 

 the roots of the thoracic nerve the nerve cells are confined to 



