8 DESCRIPTION OF 
Hab. Near Nashville, Tennessee. Dr. Troost. My Cabinet and Cabinet of Dr. Troost. Diam. .25, 
Length .45 of an inch. 
Remarks.—This is a short, obtuse species about the size of P. aurea, (nobis.) The 
substance of the shell is very thick for the genus, and it is much more thickened within 
the margin than any species I have observed. ‘The line along the margin of the lip is 
of areddish brown. The indentation of the columella is lower than usual. ‘The aper- 
ture is about two-thirds the length of the shell. 
GENUS LYMN/A. (Lamarck.) 
The genus Lymnea seems to be widely distributed round the globe. Lamarck de- 
scribes seven species as indigenous to France. We have had twenty-seven species de- 
scribed by Mr. Say, and other American zoologists, and to them I now propose to add 
sixteen from our own country, including several brought by Mr. Nuttall from Oregon, 
besides one taken by this traveller from Oahu. 
In the enumeration above, I include Mr. Say’s L. appressa, although my conviction has 
been for a long time that it is only the analogue of stagnals of Kurope. I have taken it 
on the St. Lawrence, and my cabinet is also possessed of American specimens from Ver- 
mont, Ohio, and Oregon. Its geographical distribution is probably wider than that of 
any other species of Lymnea. 
Lymnaa PHILADELPHICA. 
Testd ovato-conicd, tenui, striatd, nitidd, diaphand, subaured, imperforatd; spird subelevatd; suturis valde im- 
pressis; anfractibus quinis, convexis; aperturd angusto-ellipticd. 
Shell ovately conical, thin, striated, shining, diaphanous, rather golden, imperforate; spire rather elevated; sutures 
much impressed; whorls five, convex; aperture narrow-elliptical. 
Hab. River Schuylkill, near Philadelphia. My Cabinet, and Cabinets of P. H. Nicklin, and Dr. 
Griffith. Diam. .20, Length .48 of an inch. 
Remarks.—This species is about the size of, and is allied to phca and Griffithiana, 
herein described, and to modicella, (Say.) It has a more elongated aperture than Griffith- 
tana, has a smaller fold than plica, and is higher in the spire than modicella. ‘The aper- 
ture is about half the length of the shell. I procured many specimens west of Philadel- 
phia. Dr. Griffith informs me that he found them common south of the city. 
Lymn aa GRIFFITHIANA. 
Testa ovato-conicd, tenui, substriatd, nitidd, subdiaphand, luteo-corned, perforatd; spird breviusculd; suturis im- 
pressis; anfractibus quinis, convexis; apertura ellipticd. 
Shell ovately conical, thin, substriate, shining, somewhat diaphanous, yellowish horn-colour, perforate; spire rather 
short; sutures impressed ; whorls five, convex ; aperture elliptical. 
Hab. Charlotte Lake, Columbia County, New York. Dr. Griffith, My Cabinet, and Cabinets of 
Dr. Griffith, and Philadelphia Museum. Diam, .20, Length .30 of an inch. 
Remarks.—Rather a small species, differing from most in the form of the mouth, 
which is nearly a perfect ellipse. Ina perfect specimen before me the aperture within 
the margin of the lip is thickened by a raised line. The aperture is not quite one-half 
the length of the shell. I name it after R. E. Griffith, M. D., who seems to be the only 
person who has observed it. 
