160 



BRITISH MOLLUSKS. 



rapidly enlarging growth. ; the last whorl is so abruptly and widely 

 outspanned as almost entirely to cover the animal. It was well 

 distinguished from L. limosa by Lister, Linnseus, and Muller, and it 

 appears to differ from all its varieties. The surface of the shell is 

 frequently malleated by an irregular decussation of spiral ridges, 

 which become faint and finally disappear. 



The geographical range of L. auricularia abroad, is very ex- 

 tended. I give Siberia on the authority both of Middendorf and 

 Gerstfeldt, and Cashmere on that of M. Morelet, who states that there 

 are specimens in the Museum of Paris, collected in that locabty by 

 the unfortunate Jacquemont. In Britain, the species has not been 

 found north of the north-midland counties of England. 



3. Iiymnsea stagnalis. Panel Lymncea. 



Shell ; ovately turreted, compressly umbilicated, rather thin, yel- 

 lowish horny, spire produced and sharply acuminated, whorls 

 five to six, slopingly convex round the upper part, then ventri- 

 cose, striated in the direction of the lines of growth, some- 

 times evanescently obscurely irregularly ridged and malleated 

 in the opposite direction ; aperture moderate, somewhat square- 

 ly ovate, columella callously twisted, lip broadly appressly di- 

 lated over the umbilicus. 



