220 PNEUMONOBRANCHIATA, 



Fain. 4. AURICULID.E. 



The animal with an elongated foot, an elongate 

 ringed muzzle, two subcylindrical tentacles, with 

 the eyes near the inner side of their base ; body 

 spiral, placed on the centre of the foot, and 

 covered with a thin mantle, with a thickened edge, 

 which is itself covered with an external spiral 

 shell, which has a plaited pillar in all its ages. 



These Mollusca appear, by their habit and cha- 

 racter, to be exactly intermediate between the land and 

 the fresh-water Univalve Mollusca. They have the 

 sessile eyes of the Pond-snails placed behind, instead 

 of in front of the tentacles, and the subcylindrical 

 tentacles of the Land snails, but the tentacles are not 

 retractile under the skin of the neck. In the same 

 manner, the Carychia and the Acmea are terrestrial, 

 living in damp moss ; the Conovuli live in the mud 

 at the mouths of rivers, or in the sea : they seldom 

 leave salt or at least brackish water. There are some 

 foreign species which live in ponds, and have all the 

 habits of our Pond-snails, only their pillar is more 

 distinctly plaited. 



Montagu observes, " A remarkable character of 

 this shell (Valuta denticulata) is that the columella 

 extends no further than the upper part of the body 

 volution, the superior spires (whorls) being destitute 

 of any pillar or internal spiral division." This pe- 

 culiarity is common to most species of this family, 



