196 LIMKEAD.E. 



The spire of the shell is sometimes eroded, and 

 because the specimens which Mr. Jeffreys observed 

 in this state were a little more ventricose, he has 

 described them as a different species. 



The foot is divided transversely very deeply, as in 

 Pedipes ; it is very slow in its motion in conse- 

 quence of a double action of the foot being necessary 

 to effect progression. 



Fam. 5. LIMN^EAD^E. 



Animal with an elongate foot, a more or less conical 

 spiral body, a short muzzle, with dilated lips 

 and compressed tentacles, with the eyes near 

 the inner side of their base : the mantle, which 

 covers the body, has a thin edge and is pro- 

 tected by a variably shaped pale uniform- 

 coloured shell, which is clothed with a hard 

 olive periostracum. 



They live in ponds and ditches, often floating on 

 the surface of the water, their back downwards, or 

 crawling on the mud at the bottom, or on aquatic 

 plants, but always coming to the surface to respire. 



These animals were scattered about by the Lin- 

 naean conchologists among the Helices, the Turbines, 

 the Bullce, the Nautili, and the Patella, because 

 their shells vary considerably in their shape and 

 form; they form, however, a most natural group, 

 from their having very similar animals. Like water- 

 plants, they are distributed very widely, and are to 

 be found in almost all parts of the world. 



