274 Mr. R. Warington on the Habits of the Water-Snail 



nience, it does offer a means of researcli which should de- 

 velope some most interesting and important results, and that 

 the same principle is capable of being extended to a much larger 

 scale; a demonstration of which I believe will be very speedily 

 exhibited. As regards the growth of the plants employed in 

 these miniature ponds, I have already briefly treated in the 

 ' Garden Companion ^ for January last, and shall therefore confine 

 myself in the present communication to the two other members 

 of the circle ; and first — 



The Water-Snail. This important element in all the cases 

 where the removal of the decaying vegetable matter, or the 

 growth of Confervse, is necessary, to enable the generality of fish to 

 live healthily, as must arise in most stagnant waters and ponds, 

 offers to our consideration some very interesting phsenomena. 

 In commencing my experiments in the early part of 1849, I had 

 employed the Limnea stagnalis for this purpose, but was soon 

 obliged to substitute some less voracious inhabitant for my small 

 domain, for I found that as it grew in size its appetite increased 

 to an enormous extent, and the plants were punished most 

 severely, the leaves of the Vallisneria spiralis being bitten quite 

 through ; and if the snails were in too large a number, the whole 

 of the vegetation was rapidly removed; other varieties of the 

 Limnea were consequently introduced at an early period, namely 

 L. auricularia and L. glutinosa, as also Physa fontinalis, Bithinia 

 tentaculata, Planorhis corneus and P. carinata. These last two 

 varieties have been found highly serviceable, as from the cor- 

 nuated formation of their shell and small mouth, the fish can- 

 not so readily get them out to feed upon. With the L. auricu- 

 laria and L. glutinosa this is easily effected in consequence of 

 the large aperture of their shell; and if the fish fails in his en- 

 deavours by a sudden attack to shake the snail out, he will attempt 

 to suck it from its retreat, as is the case with the gold-fish ; with 

 the minnow (Leuciscus Phoxinus), however, it is different, as the 

 smallness of its size renders this manoeuvre impossible, unless 

 the snail be very minute; it has recourse therefore to another 

 and quite as efficient a means of obtaining its object, and I have 

 seen these beautiful little fellows seize on their prey and shake 

 it, as a terrier dog would a rat, between a piece of the rock- 

 work and the glass, until they have broken its thin and delicate 

 shell to pieces, and having effected this to their satisfaction, 

 quietly consume their victim. 



It will be seen from these facts, that the snails will require to 

 be renewed at intervals, particularly as I have previously shown 

 that the increase of the snail by its eggs, which are deposited in 

 very large quantities, is entirely prevented from the fish con- 

 suming them the instant they exhibit signs of locomotion. 



