DANFORTH: NEW PTEROPOD. 9 
are situated above the esophagus, the pleural beside it, and the remain- 
ing pairs below. 
The cerebral and pedal ganglia are practically symmetrical but the 
visceral ganglia are asymmetrical in shape, size, and position. The 
one on the right is more nearly spherical and gives oflF but a single 
nerve, while the one on the left is larger, irregular, and somewhat 
elongated, and gives off three nerves. Correlated with this asymmetry 
in the visceral ganglia there is a slight asymmetry in the pleural. The 
nature and extent of this asymmetry are shown in figure 8 (pi. 3) which 
gives a diagrammatic representation of the central ganglia as seen in a 
posterior view. 
Strong commissures unite the ganglia of each pair except the pleural, 
which naturally are unconnected. Pelseneer and others have found a 
small second pedal commissure in other pteropods but in this form I do 
not find anything that I can interpret with certainty as such a com- 
missure. One of the sections, however, shows what may be a delicate 
nerve strand running between the two pedal ganglia close to the pri- 
mary commissure. This second commissure, if indeed it be such, may 
perhaps have been torn in sectioning the other specimens owing to the 
small size of the animal and the delicacy of the structure. 
The ganglia of the same side are connected with each other by the 
usual connectives: cerebro-buccal, cerebro-pedal, cerebro-pleural, 
pleuro-pedal, and pleuro-visceral. With the exception of the first, all 
of these connectives are short, bringing the central nervous system 
into a compact form. The cerebro-buccal arises from the antero- 
lateral side of the cerebral ganglion and runs forward to the buccal 
located below the esophagus in front. It is of rather small diameter 
and slightly elongated. Just behind and a little below its origin there 
arises a cerebro-pedal connective which enters the pedal ganglion 
dorsally. This is much shorter and larger than the former. The 
cerebro-pleural still farther back is very short as is also the pleuro- 
pedal which arises from the anterior side of the pleviral ganglion and 
immediately enters the pedal. The pleuro-visceral connective is but 
little longer than the two preceding and arises ventrally from the 
pleural ganglion and enters the visceral on the dorsal side. Figure 9 
(pi. 3) represents the central nervous system in diagrammatic form 
as seen from the side. 
Besides the connectives already enumerated, there arise from each 
cerebral ganglion five nerves, two somewhat dorsally and three from 
