OF CONCnOLOGY. Ill 



DESCRIPTIONS OF NEW FLUVIATILE MOLLUSCA, 



BY GEORGE W. TRYON, JR. 



1. Melania pr^mordica, Tryon. — t. 10, f. 3. 



Description. — Shell ovately conical, robust, covered with 

 regular, close, curved growth lines, and with rounded revolv- 

 ing ribs, of which seven are on the body whorl ; spire conical 

 elevated, ? (eroded), suture deeply impressed ; whorls convex, 

 surface formed into a succession of planes by the revolving 

 ribs; aperture ovate, a little broadly effused below; the ribs 

 form slight sulcations within the aperture. Reddish-brown, 

 sometimes dark greenish-brown ; internally white or light yel- 

 lowish, the sulcations deep brown. 



Dimensions. — Length (eroded) 30 mill. ; diameter 22 mill. 



Habitat. — Burmah. 



My cabinet. Cabinets of Isaac Lea, Philada., and Charles 

 M. Wheatley, Phoenixville, Penn. 



Observations. — This is a very remarkable species. There 

 are very few which possess revolving ribs, and in all those 

 previously known they are tuberculate. In general form and 

 color this species resembles M. gloriosa, Anth., described in 

 vol. i. of this Journal, but it is a much smaller species. In 

 ornamentation it is nearest, perhaps, to J/, lyrata, Menke,* but 

 is a larger, stouter species, without tuberculatious. 



I owe to Isaac Lea, Esq., the opportunity of describing this 

 interesting exotic species. 



2. Lymn'^a(Limnophysa) Shurtleffii, Tryon. — 1. 10, f 4, 5. 



Description. — Ovate-cylindrical, rather thin, diaphanous, 

 minutely concentrically striate • spire moderately elevated, 

 apex acute, suture impressed ; whorls six, flatly convex, the 

 last one three-fourths the length of the shell, subcylindrical, 

 compressed on the sides ; aperture one-half the total length, 

 contracted, somewhat ear-shaped, columella with a considera- 

 * Reeve Gonch. Icon. Melania, fig. 170. 



