144 NEW UNIONID^, MELANID^, ETC., 



Eah. — Tennessee, Prof. Troost. 



My cabinet. 

 Diam. -30, Length -51 inch. 



Remarks. — This is one of the many species sent to me long since by my excellent 

 friend the late Prof. Troost. There were but two specimens, and as they had very 

 much the aspect of young Melania {Trypanofitoma) conica, Say, I refrained from de- 

 scribing them in hopes that others would be received. Feeling satisfied that it is a 

 distinct species, I propose the name from its round short form, somewhat like a 

 turnip. One of the specimens has a purple spot at the base of the columella ; the 

 * other is devoid of it. The aperture is quite one-half the length of the shell. 



Tetpanostoma Ltonii. pi. 23, fig. 55. 



Testa IsBvi, conica, viridi-cornea, evittata ; spira subelevata ; suturis impressis; anfractibus instar senis, 

 coQvexis ; apertura parviuscula, rliomboidea, intus albida; labro acuto, valde sinuoso; columella 

 alba, inferne incrassata et contorta. 



Shell smooth, conical, greenish horn-color, without bands ; spire somewhat raised ; 

 sutures impressed ; whorls about six, convex ; aperture rathe!" small, rhomboidal, 

 whitish within ; outer lip acute, very sinuous ; columella white, thickened below 

 and twisted. 



Operculum ovate, very dark brown, with the polar point on the basal margin at 



the left. 



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



Sab. — Cumberland River near the Ford, north side of the mountain, and Big 

 Creek, south of mountain at Cumberland Gap, Tenn., Maj. S. S. Lyon, U. S. E, 



My cabinet and cabinet of Major Lyon. 

 Diam. -32, Length -85 inch. 



Remarks. — ^^Quite a number of specimens were sent to me by Major Lyon, from 

 both the above habitats. They are all very much the same in color and size, and 

 none are banded. None were perfect at the apex, but the upper whorls, I think, 

 from indications in a few specimens, will be found to be carinate. It is between 

 Christyi and modestum (nobis). From the former it differs in having the base of the 

 columella less twisted, in having a smaller aperture, and having the whorls more 

 convex. From the latter it differs in being a smaller species, being darker, and 

 having a less expanded outer lip. The aperture is about one-third the length of the 

 shell. I name this after Major S. S. Lyon, of the Engineer Corps of the U. S. Army, 

 being collected by him during the cajnpaign last year to Cumberland Gap, East 

 Tennessee, where he obtained several new Melanidse. 



