ARIOLTMAX. 247 



nevertheless it may prove to be a variety only of th'it species. 

 Dr. Cooper says that the young, just hatched, is pale yellowish, 

 with pellucid whitish spots, and when an inch-and-a-half long 

 is colored like the adult, while the shell is perceptible through 

 the thin shield. The eggs are laid from April to June ; " they 

 have a shelly but tough envelope, and, after they are laid, the 

 shell is often entirely wanting in the parent, having apparently 

 been absorbed to form the egg-shells." 



A. NIGER, Cooper. PL 59, figs. 55, 56. 



Body long and narrow, blunt before, but little attenuated and 

 bluntly truncated behind, but with the termination of the body 

 not arched down to the tail as in Columbianus and Calif ornicus, 

 but rather erect, giving the appearance of being cleft, and show- 

 ing much more plainly the caudal gland ; mantle quite small, 

 bluntly rounded before and behind; color leaden below, blackish 

 above. Length, 2'5 inches. California. 



Distinguished by smaller size, dark colof and bluntly truncated 

 posterior termination, which is decidedly cleft at the mucous 

 pore. The genitalia also present distinguishing features from 

 the preceding forms. 



A. HEMPHILLI, W. G. Binney. PL 59, fig. 5T. 



From 25 to 31 mill, long, of a transparent flesh-color, much 

 more slender than the other known species, with a much more 

 pointed tail ; the mantle is also longer. 



Niles Station, Alameda Co., Gal. 



u These characters, even in specimens preserved in alcohol, 

 readily distinguish the species. On dissecting the specimens, I 

 also found distinguishing characters in the genitalia." BINNEY. 



A. ANDERSONI, Cooper. PL 59, figs. 58-60. 



Shield strongly granular-rugose, the respiratory orifice nearly 

 median on its right margin; tail acute, with small gland; reddish 

 gray, the body somewhat clouded with black, the shield paler, 

 clouded, or more usually with a dark band on each side above 

 the respiratory orifice, converging in an elliptic form ; a pale 

 dorsal streak; head uniform pale brown, tentacles darker; foot 

 and often the mantle tinged with olive. Length, 2'5 inches. 



California. 



This species is said to have the appearance of the figure of 



