OF NORTH AMERICA. 161 



ECOLOGY: Not recorded. Hemphill says: "Found on the shores 

 of the above lake in November, 1889. I found two living specimens 

 in the lake." 



REMARKS: Occidentalis is one of the most characteristic of the 

 American races of Lymncea. The short, acute spire with its peculiar 

 shoulder just above the suture, the suddenly expanded body whorl 

 with its pronounced shoulder, easily distinguishes it. Its nearest rela- 

 tive is sanctamaria, in which the whorls are not angular and the spire 

 is longer. There is some distortion in the aperture, especially in the 

 anterior margin; the spire also varies in height. 



Occidentalis is strongly suggestive of some individuals of the 

 European lacustris Stud., but in occidentalis the spire is longer and 

 more acute and the shoulders of the whorls are sharper than in the 

 specimens of lacustris which the writer has examined. Some of the 

 short-spired forms of European stagnalis are beautifully illustrated by 

 Nordenskiold in Bihang till Kong. Svenska Vetenskaps-Akademiens 

 Handlingar, Band 26, Afd. IV, No. 11, Tafl. 1. The plate well illus- 

 trates the large amount of variation to which stagnalis is subject. 



Lymnaea lepida Gould. Plate XXIII, figures 6-7. 



Limnaa lepida GOULD, Proc. Bos. Soc. N. H., II, p. 211, 1847 ; Moll. Wilkes 

 Exp., p. 121, figs. 141, 141a, 1852. BINNEY, Check List, p. 12, I860. CPR., Rep. 

 Brit. Ass., 1864, p. 673. TRYON, Amer. Journ. Conch., I, p. 247, 1865. BINNEY, 

 L. & F.-W. Sh. N. A., II, p. 29, fig. 33, 1865. COOPER, Proc. Cal. Acad. Sci., 

 IV, p. 95, 1870. TRYON, Con. Hald. Mon., p. 93 (67), pi. 16, figs. 12, 13, 1872. 

 CPR., Smith. Mis. Coll., p. 159, 1872. STEARNS, Proc. Nat. Mus., XIV, pp. 101, 

 102, 1891; N. Am. Fauna, VII, p. 275, 1893; Proc. Nat. Mus., XXIV, p. 291, 

 1901. KEEP, West. Amer. Sh., p. 314, 1904. 



Lymncea lepida BALL, Land & Fresh- Water Moll., p. 67, fig. 43, 1905. 



Limnea lepida GOULD, Otia. p. 41, 1862. CARLTON, Proc. Cal. Acad. Sci., 

 IV, p. 51, 1869. 



SHELL : "Very fragile, elongated, very acutely conical, subumbili- 

 cate, pale horn color ; whorls five, oblique, moderately convex, forming 

 an accumulated spire; suture moderately impressed; surface smooth 

 and shining, lines of growth faint, and when examined by a magnifier 

 they are found to be rendered somewhat zigzag by distant, revolving 

 furrows, which cross them. Aperture large and expanded, nearly semi- 

 circular, half the length of the shell; outer lip expanded; columella 

 having a very strongly marked sharp fold, and broadly covered with 

 thin callus, which not being closely appressed at the umbilical region, 

 leaves a small chink. Length, 3/5, breadth 1/4 inch." (Gould.) 

 Length. Breadth. Aperture length. Breadth. 



12.00 5.25 6.00 2.75 mill. Type (5541). 



12.00 6.00 " Gould. 



