THE TANGANYIKA PROBLEM. 
2 55 
the walls of the body, and then bend down, uniting with 
each other below the mouth. This connection appears, 
therefore, to be unquestionably the labial commissure 
described by Bouvier as characteristic of a number of the 
Archi-tsenioglossate and Rhipidoglossate types. 
The cerebro pedal connectives are long, and altogether 
the length of the cerebro-pleural, cerebro-pedal, and pleuro- 
pedal connectives gives to the nervous system the longi- 
commissurate character described by Haller. 
The pedal ganglia (Fig. 37) are united by a rather small 
connection, and are prolonged into the foot along the course 
of two well-developed scalariform pedal cords. Between 
these pedal cords there exist ladder-like connections 
similar to those found between the pedal cords of 
Cyclophorus. 
The otocysts in Nassopsis are relatively immense. They 
are situated well up on the course of the pedo-pleural con- 
nectives, and the otocyst nerves pass obliquely from them 
towards the cerebral ganglia. The otoliths are small, 
numerous, and rectangular, with the faces slightly convex. 
The reproductive apparatus in Nassopsis is somewhat 
Fig. 38. — The animal of Nassopsis nassa removed 
from its shell to show the characters of the 
operculum, op. 
