250 I HE CHICAGO ACADEMY OF SCIENCES. 



Tennessee: Hickman Co. (Hinkley). 



Geological Range: Unknown. 



Ecology : In more or less swampy brooks and streams, in situ- 

 ations similar to those in which Galba parva is found. 



Remarks: This curious Lymnjeid was at first thought to be 

 Lea's cxigua, but his description does not cover the present species 

 and the figure in Binney is totally unlike it. The type of cxigua is 

 not in existence, so that no direct comparison is possible. Stcrkii 

 bears a superficial resemblance to owascoensis, but in that species the 

 whorls are decidedly and strongly shouldered, causing them to appear 

 like boxes of diminishing size set one upon another, the whorls being 

 very flat-sided. The inner lip is also very different in stcrkii. It may 

 be distinguished from parva by its larger shell, generally more flat- 

 sided whorls and differently shaped aperture, the inner lip being 

 broadly reflected, forming a flat, concave expansion; the lower part 

 of the aperture in stcrkii is broadly effuse and produced, while in parva 

 it is very evenly elliptical. This peculiarity of the lower part of the 

 aperture, together with the broad, flat, inner lip, will usually distin- 

 guish stcrkii from related species. The presence of intermediate 

 forms suggests that stcrkii is a race of parva rather than a distinct 

 species. There is considerable variation in the height of the spire 

 and in the width of the shell, some individuals being very narrow, 

 while others are quite obese, but all agree in the form of the aperture 

 and of the inner lip. The figures well illustrate this variation. 



The variety is named in honor of Dr. Victor Sterki, of Xew 

 Philadelphia, Ohio, who collected the type lot. 



Galba owascoensis (Baker). Plate XXIX. figures 23-25. 



Lymncea ozcascoensis Baker, Nautilus, XVIII, p. 141, April, 1905. 



Limnea owascoensis Henderson, Nautilus, XX, p. 98, 1907. 



Limncea owascoensis Letson, Bull. Buf. Soc. Nat. Sci., IX, p. 242, 1909. 



Shell : Small, elongate, turreted, rather thin ; color light yellow- 

 ish horn ; surface shining, marked by close-set lines of growth ; in 

 some specimens there is a tendency to become malleated ; nucleus 

 small, round, of the same color as the rest of the shell, in form similar 

 to that of Galba parva, the first whorl being smaller ; whorls six, 

 strongly shouldered, rather flat-sided ; spire elongated, sharply conical ; 

 sutures deeply impressed; aperture roundly ovate, almost continuous, 

 about one-third as long as the entire shell ; outer lip thin, sharp ; inner 

 lip reflected over the umbilicus to form a rather wide, flat projection, 

 which is almost erect and strongly emargines the umbilical chink; 

 the callus on the parietal wall is generally rather thin, but when heavy 



