98 OPISTHOBRANCHIATA OF BRAZIL 



is worthy of separate notice, however. I am unable to confirm 

 Trinchese's figures as to its origin in either species. He shows 

 it as arising from the lower outer margin of the pedal ganglion 

 as a pedal nerve. According to my preparations and sections it 

 is a nerve from the cerebro-pleural complex, its fibres penetrating 

 the capsule of the pedal ganglion at the upper inner border of the 

 latter, immediately above the connectives joining the pedal gan- 

 glion to the cerebro-pleural complex. The fibres do not enter 

 the pedal ganglion, however, but course directly into the pleural 

 portion of the cerebro-pleural group. A similar relation may 

 also be suspected in Sp. inornata in the case of the nerve num- 

 bered 6, in fig. 36 of PI. Ill, in Vayssiere's "Recherches sur les 

 Mollusques Opistobranches du Golfe de Marseille, Supplement." 



A decided asymmetry is to be noticed in the nerves of the 

 pedal ganglia upon the two sides. Whether this has any special 

 significance or not could not be determined by the dissection of 

 but one specimen alone. 



Counting the olfactory stalk as a nerve we have seven 

 nerves given off from the cerebro-pleural complex, five of which 

 arise from the cerebral portion, one from the intermediate zone 

 between the cerebral and the pleural regions, and one from the 

 pleural alone. As the optic and otic ganglia are sessile, they are 

 not included in the above enumeration. From the pedal ganglion 

 two large nerves arise, which are distributed to the sole of the 

 foot. The peripheral distribution of the nerves was not worked 

 out in detail, such an undertaking requiring much more material 

 than was available. 



REPRODUCTIVE SYSTEM. 



The hermaphroditic gland is made up of eight spherical 

 lobules, closely packed together and more or less flattened by 

 mutual pressure. Six of these are paired, alternating more or 

 less in position, while the seventh and eighth are unpaired. The 

 .glans penis is short and conical and entirely unarmed. The re- 

 maining organs of the reproductive system are not greatly 

 different from those of the other species of Spurilla, all of which 

 seem to show close similarity. 



The general differences shown by this specimen in anatomi- 

 cal organization, especially as shown by the mandibles and radula, 



