114 THE NAUTILUS. 



4|, more or less flattened laterally and inclined to be shouldered ; 

 smooth ; suture deep ; spire short, less than one-third of the entire 

 length, apex obtuse ; aperture small, ovate, angled above, rounded 

 below, flattened on the parietal margin, which is quite oblique to the 

 axis. Peristome thick, continuous, entirely free from contact with 

 the body-whorl in fully mature specimens. 



Alt. 3^, diam. 2^-, length of aperture 1^ mill. 



Alt. 3, diam. 2, length of aperture 1^ mill. 



Habitat: Goat Island, Niagara River, N. Y. 



Amnicola sheldoni Pils. is the only species with which this can be 

 compared. The present species, however, is to be distinguished by 

 its flattened, shouldered whorls, deeper suture and more acuminate 

 spire. Six mature examples were found which, though differing 

 somewhat in the relative proportions of length and width, are, as a 

 whole, quite uniform. In four of them, the peristome is distinctly 

 separated from the body-whorl ; in one, while continuous, it is so 

 close as to be almost adnate, while in the remaining specimen, the 

 parietal margin, although somewhat broken, seems to have been 

 appressed to the body-whorl for a short distance. Associated with 

 these specimens were two other examples quite similar, but much 

 more cylindrical in outline, less solid, and with the aperture less 

 angled posteriorly. Neither is quite mature, judging from the thin- 

 ness of the lip. In view of the considerable variation in these par- 

 ticulars in other well-known species of the genus, such as Amnicola 

 lustrica Pils. and of the few specimens now at hand, it is not deemed 

 advisable at the present time to do more than call attention to the 

 fact. Dr. Pilsbry, to whom some of the specimens were submitted, 

 suggests that, like Pyrgnlopsis mississippiensis Pils., it is probably 

 an extinct species, and will be found in some quarternary bed along 

 the Niagara or some tributary creek. 



The type specimens were collected by Miss E. Jennie Letson, 

 of Buffalo, N. Y., and the species is named in her honor. 



EXOTIC MOLLUSKS IN CALIFORNIA. 



BY .TOSIAH KEEP. 



In a recent pamphlet, Mr. R. E. C. Stearns speaks of twelve 

 exotic species of mollusks that have been found in California. Sev- 



