182 FEESH-WATER AQUABIA. 



elliptical capsule: they are hatcted in from sixteen to twenty 

 days. 



Limnxa palustris (Fig. 121) is rather an elegant snail, but 

 it is too great an eater of useful growing plants to be safely 

 trusted for long in an ordinary aquarium. There are occasions, 

 however, upon which it may be of use, such as when there is 

 an excess of vegetation. It is always, I think, interesting. 



The tank in which it is kept 

 should be covered, or it will be 

 very likely to escape and die. 

 It is found in the lakes, ponds, 

 ditches, and sluggish streams of 

 nearly every pai-t of Britain. 

 The animal is of a daz-k grey 

 colour, tinged with violet, and 

 spotted with black or yellow. 

 The tentacles are conical. The 

 FIG. 121. LiMNjjA PALUSTRIS. ^isc is slightly notched. The 



shell is about Jin.- in length, 

 conical in shape, and of a light or darkish horn-colour. There 

 are six or seven whorls : the body- whorl more than equals 

 half the shell. The sutures are rather deep, and the aperture 

 is oval or almost so. This snail lays from sixty to eighty eggs, 

 and incloses them in a somewhat cylindrical capsule. The fry 

 are hatched in from sixteen to twenty days. 



Limnxa peregra (Fig. 122) is a rather handsome snail, and 

 is perhaps commoner than any other aquatic mollusc. Some 

 people do not give it a very good character as an inmate of 

 the aquarium, but I am never without it, and find that it 

 does more good than harm. I have just examined seven 

 aquaria, large and small, in which snails of this species are 

 kept, and have found only one solitary individual, out of the 

 many, upon any of the plants. All the others seemed to be 

 busy at work upon the sides of the tanks. These molluscs 

 are good scavengers, as they are not at all unready, as I . 

 have said, to become occasionally carnivorous. They will eat 

 a dead worm, a defunct fish, or even a deceased relative. 

 They are most prolific, and thus provide a great quantity of 



