NIAGARA FALLS AND VICINITY 24I 



Genus amnicola Gould & Haldeman. 1841 



Shell small, short, subglobular, and ovate; spire obtuse; shell 

 -smooth, thin and perforate; aperture ovate; lip thin; operculum 

 corneous. 



Amnicola limosa (Say) Hald. 1844. Paludina limosa 

 .Say (1817. Acad. uat. sci. Phil. Jour. 1:125). Amnicola 

 limosa Haldeman (1844. Monograph pi. 1, fig. 5, 6) 



Shell small and conic; whorls four, rapidly diminishing; apex 

 acute, suture deep ; umbilicus narrow and deep ; surface smooth ; re- 

 cent specimens show growth lines; aperture oval, slightly angulated 

 at the junction of the body whorl; lip simple. 



Found in the gravel pit on Goat island. 



Amnicola letsoni Walker 1901 (Fig. 165) 



A. letsoni Walker (Feb. 1901. Nautilus) 



Shell small, elevated and thick; whorls four or five, more or less 

 flattened, and inclined to be shouldered; suture deep; 

 spire short, less than one third the entire length; apex 

 obtuse; aperture small and oval, angled above, rounded / A 

 below, flattened on the parietal margin; lip thick and free ^*4y 

 from contact with the bodv whorl. , Pi f- \ 6 l A ™- 



-' nlcola letsoni 



Locality. Goat island. xS 



In his notes Mr Walker says : "Amnicola sheldoni Pils. 

 is the only species with which this can be compared. The present 

 species 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 pro- 

 portions 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 specimens 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 ex- 

 amples quite similar, but much more cylindrical in the outline, less 

 solid, and with the aperture less angled posteriorly. Neither is 

 quite mature, judging from the thinness of the lip. In view of the 

 considerable variation in these particulars 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." 



What may prove to be other species of Amnicola has been 

 found, but too badly worn to justify description. 



