408 



Mr. G. C. Robson on the 



2. Oloc/jsts. — Tliese arc found in the usual position on tlie 



posterior surface of the pedal ganglia. They contain 

 a single otolith. The auditory nerve is very difficult 

 to follow, and is apparently fused with the cerebro- 

 podal connective. 



3. Ei/es. — These are situated at the base of the tentacles 



and on the outer side. They consist of inner and 

 outer cornea, a well-developed lens, and retinal layer. 



(b) Ganglia and Nerves. 



The cerebral ganglia are elongate and rather pointed ante- 

 riorly. They are placed with their long axes parallel to the 

 main axis of the pharynx. They are connected in the median 

 line by a small commissure. The pleural ganglia are closely 

 applied to the cerebral ganglia, but are not fused to the latter. 

 There are very short but distinct cerel)ro-j)leural connectives 

 [cf. discussion upon the latter in Faludestrina ulvce, Bobsbn 



(12)]. 



Flo-. 5. 



9o<r 



H. nosojyJiOi-a, Cere')ro-pleural connective, 

 jy)/ = iiolit plein-al ganglion ; }rff = Y\ght cerebral 

 2)pc and c/;c = pleural-pedal and cerebro-pedal connectives. 



The cerebro-pedal and pleuro-pedal connectives are distinct, 

 though very closely applied to each other. The pedal 

 ganglia are rather round. They are closely approximated, 

 being joined by a small commissure. 



The supra-intestinal ganglion is joined to the right pleural 

 ganglion by a commissure slightly longer than that figm-ed 

 by IBregenzer for BijthineUa dunkeri (3). From this ganglion 

 are given oft the osphradial nerve and a connective to the 

 abdominal ganglion. 



The subintestinal ganglion is very closely approximated to 

 the left pleural ganglion, but not fused to it. 



