28 Journal of Comparative Neurology. 



its front (cephalic) border extends a chain of ganghonic cells. 

 The chain of cells is a portion of the antennary ganglion [fig. 3]. 



As in all invertebrate nervous systems, so here, the central 

 nervous system is composed of two things : nerve cells and 

 neuroglia (" Punktsubstanz " of Leydig, " Marksubstanz " of 

 Dietels and Ravvitz, "central Nervennetz " of Bellonci and 

 Haller). In the supra-oasophageal ganglia of Cypris the nerve 

 cells are aggregated in the dorsal, cephalic, ventral and lateral 

 portions of the periphery, while the neuroglia is central. 



Ventral Nerve Cord. — In his comparative anatomy. Pro- 

 fessor Lang has said : " The ventral cord of Cythere which fol- 

 lows the brain and oesophageal commissures is said to consist of 

 an infra-oesophageal ganglion and four subsequent ventral gan- 

 glia. The infra-oesophageal ganglion is said to show its com- 

 position out of two ganglia and to innervate the jaws, while the 

 three subsequent ganglia give off nerves to the limbs, and the 

 last ganglion nerves to the most posterior division of the body 

 and genital apparatus. In contrast with the above, the ventral 

 chain of Halocypris appears much concentrated. It consists of 

 an infra-oesophageal ganglion, with nerves to the jaws and max- 

 ilHpeds, and a small ventral ganglion. Out of the latter arise 

 two pairs of nerves, which probably innervate the musculature of 

 the limbs and abdomen." 



Morphologically the ventral chain of Cypris is intermedi- 

 ate between these two extremes. It is more concentrated than 

 that of CytJicre but not quite so compact as that of Halocypris. 

 In this case the ventral chain consists of an infra-oesophageal 

 ganglion and two subsequent ventral ganglia. All of these 

 nerve ganglia are connected, not only by two longitudinal com- 

 missures, but also by straggling chains of nerve cells [fig. 

 32, 42]. To repeat, the ventral chain of Cypris is composed of 

 three pairs of ganglia, which are united by commissural fibres 

 and nerve cells. 



Now Wenzel Vavra has recently stated that the ventral 

 chiia of Cypris \i coiiDosed of five ganglia. At first blush 

 these two views seem to be irreconcilable. However, when crit- 

 ically compared, the two views are not so antagonistic as they 



