68 LIMN^ID.^. 



GENUSIV.—AN'CYLUS* GEOFFROY. 



Body more or less oval, conical, flattened beneath ; tentacles 

 subcylindrical, short ; respiratory orifice in the form of a short 

 tube ; foot oval, rather shorter than the body, to which it is 

 attached by a rudimentary pedicle or stalk. 



Shell cowl-shaped ; spire rudimentary, dextral, or sinistral. 



The animals which belong to this genus usually 

 inhabit clear water, attaching themselves to stones or 

 the leaves and stems of aquatic plants. They crawl 

 along in a very leisurely manner, twisting their shell 

 slowly from side to side as they advance. In Gray's 

 edition of Turton's ' Manual ' (1840, p. 248) it is stated 

 that "these animals sometimes swim about on the 

 surface of the water like Limnaei, with their backs 

 downwards." Moquin-Tandon, Gwyn Jeffreys, and 

 other writers affirm, however, that they do not float, 

 nor have I ever observed them in a floating position. 

 They feed upon Confervae and other water plants, 

 and upon decomposing vegetable substances. Their 

 stomach is often filled, like the gizzard of a fowl, with 

 minute particles of fine gravel or sand, which are 

 doubtless of service to the animal during the process 

 of digestion. The capsules in which the eggs are 

 deposited are attached to stones and other submerged 

 objects. 



In Tate's ' British Mollusks ' it is stated that the 

 two species (by which this genus is represented in the 

 British Isles) differ considerably from each other in 

 their lingual dentition. In A . fliruiatilis ''the central 

 tooth is minute, the lateral teeth, thirty-seven in 



Curved or hooked (like the eagle's beak). 



