LYMN^EHLE OF NORTH AMERICA. 409 



Limnophysa emarginata Beck, Index Moll., p. Ill, 1837. — Tryon, Amer. 

 Journ. Conch., I, p. 252, 1865 (part).— DeCamp, Kent Sci. Inst., Mis. Pub. No. 5, 

 p. 8, 1881 (part).— Rep. N. Y. State Mus., XXV, p. 112, 1882.— Grant, Rep. Nat. 

 Hist. Surv. Minn., XVI, p. 483, 1888. 3 



Limnea serrata Haldeman, Mon. Lim., p. 12, pi. 2, figs. 6, 7, 8, 1842. 



Limncea serrata Binney, L. & F.-W. Sfa. N. A., II, p. 52, fig. 78, 1865.— 

 Tryon, Amer. Journ. Conch., I, p. 253, 1865; Con. Hald. Mon., p. 110 (84), 

 1870. 



Limnophysa ampla var., Rep. N. Y. State Mus., XXXV, p. 112, 1882? 



Radix ampla Morse, Journ. Port. Soc. N. H., I, p. 42, 1864 (part) ; Bull. 

 Essex Inst., XII, p. 172, 1880 (part). 



Limncea delicata 'Say', Sowb., Conch. Icon., XVIII, Limn., sp. 76, pi. 12, 

 figs. 76, a, b, 1872 (not described by Say). 



Limncea emarginata mighelsi Nylander, Nautilus, VIII, p. 126, 1896; XI, 

 p. 10, 1897; XIII, p. 104, 1900 (part).— Baker, Bull. Chi. Acad. Sci., II, p. 196, 

 pi. 2, 1900 (part).— Nylander, Dist., pis. 2-4, 1901 (part). 



Shell : Large, ranging from ovate to somewhat globose, inflated, 

 usually rather thin, more or less translucent; periostracum corneous, 

 varying from almost pure white to rather dark brown; the perios- 

 tracum is sometimes ornamented by longitudinal lighter bands, much 

 narrower than the ground color of the shell; frequently there will be 

 a broad band of white on the last whorl, and the sutures are sometimes 

 bordered by a white line; nuclear whorls 1^2 large, wide and low, 

 flattened, chestnut colored, in outline resembling those of Galba nasoni ; 

 surface dull to shining, lines of growth coarse, crowded, frequently 

 wrinkled and sometimes crossed by several spiral ridges, in addition 

 to the fine spiral impressed lines, giving the surface a malleated aspect ; 

 whorls 5 to 5^2, convex to subglobose shouldered, more or less inflated, 

 the last whorl large and usually quite convex, showing a tendency to 

 expand and flare, and also to become shouldered; spire varying from 

 broadly, acutely pyramidal to depressed globose or flattened, frequently 

 eroded; sutures generally deeply impressed in some individuals mark- 

 edly so ; aperture ovate or somewhat rectangular, very large, some- 

 what expanded or flaring in some specimens, a trifle effuse anteriorly; 

 the aperture occupying one-half to two-thirds of the length of the 

 shell; aperture whitish to brownish or deep chocolate in color; peris- 

 tome thin, with a thin whitish or brownish internal varix in fully adult 

 specimens; inner lip white, wide, rather broadly reflected and forming 

 a wide expansion which strongly emargins the umbilical chink; in the 

 majority of specimens the parietal callus is very thick and is a trifle 

 raised so as to make the aperture continuous ; the columella varies 

 from smooth to heavily plicated; the umbilicus varies from a small 

 chink to a rather wide perforation, emargined by the inner lip; axis 



3 This record has not been verified. 



