MOLLUSCA FROM JUAN FERNANDEZ AND EASTER ISLAND 



251 



In the genital organs (fig. 20) it appears, at a first glance, that the oviduct 

 is filled, in adult specimens, with a small number of enibryoes (about 6 were 

 counted), the most advanced ones measuring 0,9 mm in height and their shell 

 containing 2 V2 whorls. A spermatheca with a long stallc is present, and 

 likewise a well-developed albuminiparous gland, but no vesicula seminalis in the 

 spermoviduct. From the comparatively large prostata gland, the vas deferens 

 issues and follows the stalk of the spermatheca downwards, then the short 

 vagina, and the penis upwards, till it debouches in the proximal part of the 

 latter near its end. The penis is provided with a long and thick finger-like 

 appendix, near the base of which a thin muscle extends backwards uniting in 



Fig. 19. Teeth from the radula of Pacificella variabilis n. sp. X 750. 



Fig. 20. Genital system oi Pacificella variabilis n. sp. Marking as in figs. 11 and 15. 



Fig. 21. Nervous system of Pacificella variabilis n. sp. Marking as in fig. 16; «, arteria pedalis; 

 r. s., radula sac; s. g., salivary glands; st^ statocyst. 



a shorter or longer space with the retractor penis posteriorly. The latter is 

 attached to the diaphragma dorsally. The whole penis is situated completely 

 to the right of the eye retractor, and these latter join each other and the 

 retractor bulbi, and then attach to the columellar muscle. 



The central nervous system (fig. 21) shows 4 ganglia in the visceral loop: 

 a right and a left pleural ganglion, a left parietal ganglion, and a visceral 

 ganglion composed of the fused abdominal and right parietal ganglia. This is 

 pressed towards the right side; the same features are observed in Cochlicopa 

 (cf. Semper 1910^ fig. ']'^\ A rather long commissure exists between the 

 cerebral ganglia, but the pedal ones are lodged close side by side. 



The characters of the penis, as well as the presence of an albuminiparous 

 gland, are inconsistent with those of fam. Tornatellinidae as constituted by 



* Bronn's Klassen u. Ordnungen. III. MoUusca. Pulmonata. 



