184 FKESH-WATEE AQUAEIA. 



coui'se of a year. Dr. Jeffreys is reported to have stated that 

 L. peregra deposits about 13,000 eggs. The eggs are hatched 

 in from sixteen to twenty days. 



Limnxa glabra is an elegant little snail, found in many 

 parts of England, but more rarely in Scotland and Ireland. 

 It lives at the bottom of rather shallow stagnant water, only 

 coming, as a rule, to the surface of the water for the purpose 

 of taking a fresh supply of air. The body of the animal is 

 of a dull grey colour, spotted minutely with black. The 

 tentacles are triangular and of a lighter colour than the body. 

 The eyes are placed upon tubercles. The shell is cylindrical, 

 and not quite an inch long. There are seven or eight whorls; 

 the body-whorl does not equal half the shell. The spire is 

 produced, and tapers to a rather fine point. The aperture is 

 narrowly oval. This mollusc lays from twenty to thirty eggs, 

 and incloses them in an oblong capsule. The fry are hatched 

 in, I believe, from sixteen to twenty days. 



Limnsea truncatula is found in rather muddy water in every 

 part of Britain. It is fairly useful in the aquarium, and is 

 not likely to do much harm. The body of the animal is 

 almost black and spotted vdth black : it is of a lighter shade 

 underneath. The tentacles are light grey, and also spotted 

 with black. The shell is about 4in. in length, and oblong- 

 conical in shape. There are five or six turreted whorls. 

 The spire has the appearance of being slightly truncated; 

 hence the specific name of the mollusc. The apex is sharp, 

 the sutures are very deep, and the aperture is almost oval. 

 This snail generally deposits its capsules, containing from 

 twelve to twenty eggs, upon the mud. The eggs are hatched, 

 I believe, in from sixteen to twenty days. 



lAmnxa glutinosa is said to be "locally and periodically 

 abundant;" that is, in some localities it is common for a time> 

 then it disappears apparently altogether, only to re-appear after 

 an interval of longer or shorter duration as numerous as ever. 

 It has been suggested as a reason for this strange habit on the 

 part of the mollusc that it buries itself for some considerable 

 time in the mud at the bottom of the water in which it dwells 

 and thus escapes notice and capture. The L. glutinosa lives in 



