NEW MELANIDiE OF THE UNITED STATES. .355 



Diam. -44, Length -98 inch. 



Remarks. — This is an unusual form of Lithasia, and cannot be confounded with 

 any known species. The spire is exserted like most of the Melanidce, but the aper- 

 ture has all the characteristics of the true Lithasice. Its most remarkable character 

 is the formation of the few low, elongate tubercles which it possesses. These are 

 formed by an enlargement on the middle of the edge of the outer lip at each stage 

 of growth, — a character I have not observed in any other species of Melanidce.. 

 I suspect that that this species will generally be found to be banded. One of the 

 two specimens before me has six well-defined bands, which are indistinct on the 

 outside, but are well marked inside. The other has only one band, and this is 

 visible only on the upper whorls, — the aperture being whitish, with a brown, indistinct 

 band at the base. Tbe upper callus is well marked, and the channel below is well 

 defined. The aperture is more than one-third the length of the shell. I have 

 great pleasure in naming this fine species after Major T. C. Downie, to whom I 

 owe the acquisition of many new and rare molluscs. 



Genus STREPHOBASIS. 



Strephobasis carinata. PI. 39, fig. 228. 



Testa carinata, subfusifomii, inflata, subtermi, virente, quadrivittata ; spira obtusa ; suturis valde 

 impressis ; anfractibus seuis, planulatis, ad apieem carinatis, ultimo inflate- ; apertura submagnS,, 

 rhoniboidea, iutiis albida et vittata ; labro acuto, parum siimoso ; columella incrassata, retrorsa 

 et valde contorts,. 



Shell carinate, subfusiform, inflated, rather thin, greenish, four-banded; spire 

 obtuse ; sutures very much impressed ; whorls six, flattened, carinate at the apex, 

 the last one inflated ; aperture rather large, rhomboidal, whitish and banded within ; 

 outer lip sharp, somewhat sinuous ; columella thickened, bent back and much 

 twisted. 



Proe. Acad. Nat. Sci., 1862, p. 273. 



Hah. — Tennessee River. W. Spillman, M. D. 



My cabinet and cabinets of Dr. Spillman. 

 Diam. -20, Length "37 inch. 



Eemarhs. — A single specimen, no doubt young and somewhat fractured on the 

 outer lip, is the only one received among the shells from Dr. Spillman. The spire 

 is perfect, and all the whorls but the lowest one are carinate. It is, perhaps, 

 nearest to S. Glarhii (nobis), but may be at once distinguished by the inflated 

 form, the size and the bands. The aperture is about one-half the length of the 

 shell. 



