INTEODUCTION. 9 



keep as near to nature as possible, I have no hesitation in 

 recommending for marine-shore objects, the form of tank 

 with a sloping back. The bottom of the vessel should be 

 flat only for about a third of its width, and from that line 

 it should gradually rise towards the back ; the front being 

 perpendicular, and of clear glass. The back and sides 

 should be opaque. If in a room near a window, let the 

 back be towards the light, which will then enter only from 

 above, just as it would in a basin of rocks on the shore. 

 Slate is good for the back and sides, and plate- glass for 

 the front. Mr. Warrington is now trying deep rectan- 

 gular tanks, shaded with green coatings to modify the 

 light, and suited for animals and plants accustomed to 

 deep water. Eectangular tanks are also suitable for fishes, 

 if of any size; and as fresh- water tanks will bear more hght 

 than marine, they too may be straight- sided. 



Yases and shallow glass pans are also used both for 

 Marine and Eresh Yivaria, and will, for many purposes, 

 answer as well as the more complicated and expensive 

 forms. An Aquarium should be covered either with muslin 

 or a plate of glass. 



Fittings or Furnishing, — The bottom should be laid in 

 with sand or gravel suited to the condition they are in- 



