FAMILY LYMN^EID^E 67 



pillar gyrate, pervious, in the early whorls widely so, a condition 

 concealed in the adult. 



This form grows in a region containing little lime, and the shells 

 are extremely thin and often eroded into holes, which exhibit the 

 peculiarities of the axis by which the species is relegated to the typical 

 Lymnaeas, though externally it has much the appearance of a small 

 Radix. The species has been figured in the newer portion of the 

 Conchylien Cabinet, but I have not the reference at hand. 



Adults measure : 



*Lymnaea lepida Gould. 



Limnaa lepida Gould, Proc. Boston Soc. Nat. Hist., 11, p. 211, 1847 ; Moll. 

 U. S. Expl. Exp., p. 121, figs. 141, \\\a, 1852. — 

 Binney, Land and Fw. Sh. N. Am., 11, p. 29, fig. 33, 

 1865. 



Range. — Lake Vancouver, Oregon (Wilkes) ; near 



Challis, Idaho (Merriam) ! 



A species existing near the boundary and doubtless Fig. 43. Lytn- 



to be found in southern British Columbia. n<ea lepida 



Gould. 



*Lymnaea (Bulimnea) megasoma Say. 



Lymnceus megasomus Say, Rep. Long's Exp., 11, p. 263, pi. xv, fig. 10, 1824. — 

 Kuster, Conchy Cab., ed. 11, Litnncea, p. 36, pi. vr, figs. 20, 21. 



Limnea megasoma Haldeman, Mon. Limn., p. 13, pi. 



in, figs. 1-3, 1841. — Whitfield, Bull. Am. 



Mus. Nat. Hist. N. Y., 1, No. 2, p. 29, pi. v, 1882. 



Limnaia megastoma Sowerby, Conch. Icon., xviii, pi. 



11, fig. 12, 1872. 

 Limntza megalosoma Sandberger, Conch, d. Urw., p. 

 581, 1873. 



Range. — Northern New England, Canada and 

 British America to Lat. 57 N. 



Lake Superior! Vermilion Lake, H. B. T. ; to 

 Etchimamish Lake, in Lat. 57 between the Nel- 

 Fig. 44, Lymncea son River and the Height of Land, Keewatin ; 

 megasoma Say. Bois Blanc Lake, Manitoba ! 



The British American localities are cited from the literature, and 

 except the last I have been unable to verify them by an examination 

 of authentic specimens. 



