68 



LAND AND FRESH-WATER SHELLS OF N. A. [PART IV. 



luul lor a long time. It is one of the largest species we have in the 

 Fiff 13-' United States. It is perhaps nearest to JSIelania (Trijpa- 

 nostoma) canaliculata, Say. It is, however, more inflated, 

 the aperture is larger and the columella more extended. 

 All the specimens are not channelled, but all are more or 

 less carinate at the periphery. Two of the specimens 

 are obscurely banded 'inside, and one very much banded 

 inside and out. The old specimens are thickened inside 



the edge of the lip. The aperture is more than one-third the length 



of the shell.— iea. 



Without making a posiYive decision in this matter I am in- 

 clined to believe that T. Troostii is distinct from canaliculatum. 

 It appears to be more inflated in its form, not so flatly conical, 

 with a longer, rounded base. 



The specimens before me convince me, however, that T. vir- 

 ide and ligatum are only young shells of the same species. I 

 give Mr. Lea's descriptions of the latter two. The figures are 

 copied from his plate. 



Trypanostoma viride. — Shell subsulcate, somewhat thick, subfusi- 

 form, olivaceous; spire obtusely conical; sutures much impressed; 

 whorls seven, convex, the last slightly caualiculate ; aperture rather 

 large, rhomboidal, purple or whitish within ; outer lip acute, 

 sinuous ; columella thickened below and slightly twisted. 



Habitat. — Tennessee ; Prof. Troost, 



Diameter, "48 ; length, -89 of an inch. 



Observations. — I have about a dozen specimens before 

 me, all of which have the same olive-green hue. They 

 have been in my possession a long time, and I had put 

 them among the young of Ildania ( Trypanostoma) canali- 

 ctilata, Say. I have now no doubt but that they are distinct from that 

 large species. None of them are half the size, the color is darker 

 and they are wider in proportion. The revolving furrow above the 

 periphery of the last whorl is hardly observable in some specimens. 

 Every one of my specimens has a purplish-brown spot at the base of 

 the columella, and in some specimens this color pervades the whole 

 of the interior. The aperture is more than a third of the length of 

 the shell. — Lea. 



Trypanostoma ligatum. — Shell carinate, subfusiform, rather thick* 

 inflated, shining, with or without bands, yellowish-olive ; spire ob- 



