SNAILS AND LIMPETS. 



181 



a greyish-white or yellowish horn-colour, and is sometimes 

 covered with some extraneous substance. There are from six 

 to eight whorls, the body-whorl being much larger and more 

 swollen than the others. The spire is elongated, and tapers 

 gracefully to a fine point. The sutttres are rather deep, and 

 the aperture is almost oval. This snail incloses its eggs, some- 

 times numbering as many as 130, in an orbicular capsule. 

 The fry are hatched, according to the temperature of the 

 water, in from fifteen to twenty days. 



Limnsea awicularia (Fig. 120) has a greater liking for con- 

 fervse than L. stagnalis, and is therefore more suitable for 

 the aquarium. It is found in the sluggish sti-eams, lakes, and 

 ponds of difEerent parts of Britain, but it is not a very 



Fig. 120. LimNjEA auricularia. 



common species. Even where it does abound, it frequently 

 escapes capture, unless properly searched for, from the habit 

 it has of remaining at or near the bottom of the water. When 

 taken it is easily recognised. The body of the animal is a 

 greenish dark grey, spotted with small black spots and larger 

 white ones. The tentacles are flat, triangular, and spotted 

 with yellowish-grey on the margins. The disc has also a 

 yellow margin. The shell is about lin. long, fin. wide, and of 

 a light yellowish horn-colour. There are four or five whorls^ 

 the body-whorl being much larger than aU the rest of the 

 shell. The spire is short and the apex is much pointed. The 

 aperture is very large and ear-shaped: hence the specific name. 

 The outer lip is bent backward or reflected. L. auricularia 

 lays about eighty eggs, and incloses them in a somewhat 



