ANGITREMA. 15 



form, but the aperture is that of a Melania. I found it adhering to 

 logs iu the Tennessee River, at Florence, where it is abundant. My 

 friend, Wm. Hodgson, Jr., found it also in the Holston River, in 

 Tennessee. — Conrad. 



This species is allied to No 1, but may be distinguished by 

 its smaller size and much smaller shoulder, by its crowded 

 tubercles, and by the constant presence of one or more inferior 

 rows. On the other hand it is closely allied with L. suhglohosa^ 

 Lea. Like the former, it is a very abundant species. I think 

 th| locality in East Tennessee, quoted by Mr. Conrad, an error. 



3. A. subglobosa, Lea. 



Lithasia subglobosa, LEA, Proc. Acad. Nat. Sci., p. 55, Feb., 1861. Jour. Acad. Nat 

 Sci., V, pt. 3, p. 2G1, t. 35, f. 70. Obs., ix, p. 83. 



Description. — Shell tuberculate, subglobosa, thick, yellowish horn- 

 color, double-banded ; spire scarcely exserted ; 



' ^ •' ' Figr. 47. Fiff. 48. 



sutures impressed ; whorls five, the last very 



large, towards the shoulder tuberculate; aper- 

 ture large, rhomboidal, within white and double- 

 banded, channelled at the base ; columella very 

 much thickened above and below ; outer lip expanded, acute at the 

 margin. 



Operculum rather small, very dark brown, subovate, with the polar 

 point within the lower left edge. 



Habitat. — Tennessee; Prof. G. Troost. 



Diameter, '48; length, -60 inch. 



Observations. — Two specimens of this remarkably globose species 

 have been in my possession for a long time. I had doubts of their 

 being only the young of Melania (Lithasia) salebrosa, Conr., but they 

 are so different from any young of that species which I have seen that 

 I cannot now doubt their being entirely distinct. I know of no 

 species which has so obtuse a spire. In this it resembles Anadosa, 

 but the well characterized columella forbids its being at all confounded 

 with any species of that genus. The callus above and below is unus- 

 ually strong ; below it amounts almost to a fold. One of the specimens 

 is full grown, and has five turbercles on the shoulder of the outer half 

 of the last whorl, and near the edge there are three above those five. 

 The smaller one is little more than half grown, and has not as yet 

 formed any tubercles. The two broad bands are below the row of 



