CHIEFLY OF THE UNITED STATES. 143 



Remarlcs. — This species is allied to cylindraceum, herein described, but differs in 

 being shorter and wider in proportion. It differs also in the form of the bauds where 

 they exist. Two of the six specimens before me have a single narrow band below 

 the middle, and one has a second band above the middle. All the specimens have 

 apices so much eroded that the number of whorls cannot be correctly ascertained. 

 There may be six or seven. The aperture is probably more than one-third the 

 length of the shell. 



TrYPANOSTOMA^ CURTATUM. PL 23, fig. 53. 



Testa laevi, pyramidata, luteola, crassa ; spira obtusa : suturis irregulariter impressis ; aHfraetibus instar 

 septenis, planulatis, ultimo impresso ; apertura rhombica, intus albida ; labro acuto, expanse, valde 

 sinuoso ; columella incrassata, inflecta et valde contorta. • 



Shell smooth, pyramidal, yellowish, thick ; spire obtuse ; sutures irregularly im- 

 pressed ; whorls seven, flattened, the last one impressed ; aperture rhomboidal, 

 whitish within ; outer lip acute, expanded, very sinuous ; columella thickened, bent 

 in and very much twisted. 



Operculum ovate, (iark brown, with polar point near the base on the left. 

 Proc. Acad. Nat. Sci., 1863, p. 155. 



Hah. — Powell's River, near Cumberland Gap, East Tenn., Maj. S. S. Lyon, U.S. E. 



My cabinet and cabinet of Major Lyon. 

 Diam. -41, Length 1-75 inch. 



Remarlcs. — Quite a number of this species were sent to me by Major Lyon. It 

 is a short thick species, with a well characterized aperture, the columella being much 

 thickened, drawn back and twisted. It is allied to T. pumilum a,ndi minor, (nobis,) 

 but differs from both in having the sides flattened and being angular about the 

 middle of the body whorl. Very few of curtatum are banded, while all I have seen 

 of the above two species are banded and the epidermis polished. The aperture is 

 about one-third the length of the shell. 



Trtpanostoma napoideum. pi. 23, fig. 54. 



Testa la3vi, obtuso-conoidea, subcrassa, cornea, evittata; spira curta, mucronata ; suturis impressis; 

 anfractibus septenis, superne convesiusculis, ultimo inflate ; apertura grandi, subrhomboidea, intus 

 alba ; labro acuto, sinuoso ; columella inferne incrassata et valde contorta. 



Shell smooth, obtusely conical, rather thick, horn-color, without bands; spire 

 short, pointed at the apex ; sutures impressed ; whorls seven, slightly convex above, 

 the last one very much inflated ; aperture large, subrhomboidal, white within ; outer 

 lip acute, sinuous ; columella thickened below and very much twisted. 

 Proc. Acad. Nat. Sci., 1864, p. 112. 



