LIMNJEADJE. 249 



It is no proof that the animals do not breathe free air, 

 because they are usually observed attached to stones, 

 like PateMce, at the bottom of the water ; for Limnceus 

 pereger is more frequently found at the bottom of the 

 water on the mud than in any other place ; and I have 

 seen a specimen on exactly the same place for several 

 days, without moving. But the Ancyli are often 

 found, as has been observed by Mr. Jeffreys, out of 

 the water, and only within reach of the spray of a 

 water-fall. 



These animals are very vivacious, for a specimen 

 lived and moved about for an hour and more after its 

 shell had been completely removed. 



96. 1. AxcYLUsJliwiatiUs. Common River Limpet, 

 (t. 10. f. 125.) Shell conoid, with the point re- 

 curved and near one end; aperture roundish- 

 oval; disk blueish. 

 Ancylus fluviatilis. Milller, Verm.; Drap. p. 48. 

 t. 2. f. 23, 24. ; Brard, p. 200. t. 7. f. 3. ; Sowerbg, 

 Gen. fig. 1.; Turton, Man. ed. 1. t. 140. f, 125. 

 Patella fluviatilis. Lister ; Mont. p. 482. 



lacustris. Turt. Diet. p. 138, 



Crepidula lacustris. Fleming, Ency. 

 b. With slight longitudinal striae. 

 In streams and rivulets, attached to stones. 

 Animal greyish. 



Shell about a quarter of an inch in diameter, and 

 nearly as much in height, semitransparent, light horn- 

 colour, covered with a dusky green skin, slightly 

 marked with concentric striae, inside bluish-white, 

 glossy ; the crown slightly curved downwards. 



M. Michaud has described a specimen which has 

 M 5 



