PLATE CLXXV. 



FIG. I. 

 HELIX FRAGILIS. 



BRITTLE RIVER SNAIL, 

 GENERIC CHARACTER. 



Aperture of the mouth contracted, and lunulated. 



SPECIFIC CHARACTER 



AND 



SYNONYMS. 



Shell imperforate, ovate, tapering, round, pellucid : aperture oblong- 

 ovate. 



Helix fragilis : testa imperforata ovato-subulata tereti pelhicida: 

 apertura ovata-oblonga. Linn. Faun. Suec. 

 2\S1.—Gmel. Linn. Syst. Nat. 3658. Sp. 129. 

 Penn. PL Z6. 



Brown River Snail. Pult. Cat. p. 48. 



Helix fragilis is distinguished from Helix stagnalis, and one or 

 two other very analogous species of river snail by a number of slight 

 ridges which spirally traverse the whole shell, and are in particular 



H 3 obvious 



