230 PROCEEDINGS OF THE ACADEMY OF [1898. 



and" very short. Liver occupying posterior portion of dorsal hump 

 and spire of shell. 



Genital system with well-developed penis continued beyond inser- 

 tion of retractor in a short epiphallus. Spermatheca with a long 

 duct or one of quite moderate length ; an appendicula near the base 

 of vagina or penis, and, according to Pfeffer, two long-stalked, 

 globose, netted vaginal accessory appendages. 



Muscle system (PI. XIV, fig. 65) Ariolimacine. Buccal and eye 

 retractors converging posteriorly, contiguous at their proximal in- 

 sertions. A " retensor " arises from the roof of visceral cavity 

 slightly anterior to proximal insertion of retractors, and extends 

 anteriorly to the right side near the lower edge of mantle, where it 

 is inserted in the integument. Penis retractor inserted in the left 

 posterior region of -the visceral dome. 



Distribution, Santa Barbara Island, off California, Guadalupe Is- 

 land, off Lower California (B. notabilis), and States of Vera Cruz 

 and Chiapas, Mexico (B. Salleana, Cordovana, Sumichrasti, Chia- 

 pensis). 



The chief differences between Binneya and Xanthonyx seem to be 

 that in Binneya the nepionic shell is spirally lirate, in Xanthonyx 

 radially plicate ; in Xanthonyx there is a small caudal horn, in 

 Binneya none; and there are certain discrepancies in the details of 

 genitalia as described by Binuey, Crosse and Fischer, and Strebel 

 and Pfeffer. These may, perhaps, be in part merely specific varia- 

 tions, and in part errors of observation. On account of the sexually 

 immature condition of our specimens we unfortunately cannot verify 

 the published accounts. The description of the anatomy of Xan- 

 thonyx Salleanus given by Strebel and Pfeffer seems to be worthy 

 of confidence. 



Binneya agrees with Hemphillia in the solid tail, the viscera being 

 crowded forward into the dorsal hump ; in the exposed shell, short 

 and simple gut; the general arrangement of muscles, especially the 

 possession of a " retensor " ; in the well developed penis, and general 

 system of external reticulation. It differs from Hemphillia mainly 

 in the better developed spiral shell, the differently placed retensor 

 muscle and penis retractor, the presence of an appendicula, and the 

 distinctly tripartite sole. That the two genera are closely allied is 

 so obvious as to justify the supposition that Hemphillia descended 

 from a slug very similar to the existing Binneya. 



Cryptostrakon W. G. B. is probably allied to Binneya, but the 



