96 



THE MARINE AQUARIUM. 



keep fiddler crabs in our tank, it will be as well to have 

 some part of the bottom formed of sand, so that they 

 may burrow if they wish. 



When we have got the bottom and rockwork arranged 

 according to our taste, we introduce plants which serve 

 the same purpose in the marine collection as in the fresh- 

 water tank — that of supplying the animals with the oxy- 

 gen for their respiration — and these we procure along the 

 sea-shore. On sandy shores, we shall find the green algce 

 attached to small stones partly buried in the sand or 

 rolling about loose as moved by the waves ; these, if not 

 too large, will do excellently for rockwork, in our minia- 

 ture ocean, and they present us with the advantage of 

 plants growing on our ornamental rockwork which add 

 much to its picturesque appearance, and so we do not 

 encumber our tank with useless stones, but in this way 

 make use of every inch of room we can to bear our life- 

 giving vegetation. The red and purple sea-weeds will be 

 found on rocky shores, together with some of the green, 

 one of which, the Bryopsis pulmosa, makes a beautiful 

 ornament when introduced with taste into elevated posi- 

 tions. 



The water comes next after we have put in our plants. 

 And here I should mention that I have found it prefer- 

 able to wash the green alga) (as Ulva and Enteromoryha) 

 for about half a minute in fresh and not in salt water, 

 as the fresh water kills many minute animals that would 

 otherwise lie apt to die afterwards and foul the water. 

 I generally shake the stones which bear the plants of 

 Ulva and Enleromorpha rather roughly in the fresh water 



