28 VESSELS TOE AQUAUIA. 



of glass, either ground rough or clear— though ground 

 glass, perhaps, is the best, as it does not allow the direct 

 rays of the sun to pass through it and impinge upon the 

 water so as to heat it unduly, which would be deleterious 

 to the animals, but .rather diffuses the light so as' to make 

 it beneficial to the growth of the plants. To keep the fish 

 within fresh water Aquaria, we may use lighter covers than 

 glass ; for instance, a piece of bobbinet stretched over 

 a frame of wire. The gold-fish and dace I have found 

 most apt to leap out, and sometimes the minnows will do 

 so. Another good kind of cover can be made of perfo- 

 rated zinc ; but it should not be painted in any way, as 

 morsels of the paint will be liable to chip off, and falling 

 into the water endanger, by its presence, the health, and, 

 indeed, life of the fish. If wc use glass covers, we 

 shall, from time to time — that is to say, four or five times 

 a day — find it necessary to leave them oil", as will be made 

 manifest from the close smell perceivable on lifting them 

 off — the marine tanks especially, if there be much vegeta- 

 tion in them. 



For the purposes of Aquaria, there are used in England 

 several forms of vessels, such as vase-shaped and others, 

 besides the ones I have mentioned. And for what are 

 termed rock-pools — that is to say, shallow vessels imitating 

 the natural receptacles of that name, and used for the 

 purpose of keeping Actinia:, glass milk-pans will be found 

 very suitable : however, the form and size of the tank 

 must be left, to a certain extent, to the fancy of the 

 naturalist. 



Mr. Warrington's tank (PI. 1., Fig. 2), is of a pecu- 



