112 
THE SALT-WATER AQUARIUM. 
very considerable portion of them are found between tide-marks. The shells 
of some of the species are more spiral and acute than that of the common 
periwinkle. 
A writer, treating of this mollusk, pleasantly observes: 
“ The pleasures of a sea-side ramble are much increased by an intelligent 
observation of the various forms of animation that are met with—among 
which the periwinkles are often prominent, not only for their numbers, but 
also for their activity. They dot and stud the slimy rocks with their tur¬ 
binated shells, or creep through the tiny corallines, or slide among the 
overhanging fuci in search of food— 
* Part single, or with mate, * 
Graze the sea-weed, their pasture; 
And through groves of coral stray. 111 
GENERAL DIRECTIONS FOR MANAGEMENT. 
Do not over-crowd your aquarium at first. Introduce the animals gradu¬ 
ally, and you will be able to see, by careful watching, if any specimen is 
objectionable, by disagreeing with the rest of the inhabitants, or if the 
aquarium disagrees with him. Remove decaying weeds and drooping ani¬ 
mals at once. Never allow the full glare of the sun to rest for hours 
together on the aquarium, during a hot day; and particularly take care that 
the sun does not shine through the side of the tank. 'When the weather 
• has been dull for some days, or if the water looks turbid, you may stir it 
slightly with a small stick, taking care, of course, to avoid injuring the 
plants and animals; this will oxygenize the water, and make up for the 
deficient generation of oxygen by the plants, in the absence of sunlight. 
The water must never be allowed to get lukewarm. Avoid introducing 
voracious animals among the quietly disposed. Dust is another evil to be 
guarded against, for if it once thoroughly coats the surface of the water, it 
will hinder the oxygen of the air from mixing with it, and your creatures 
will pine and die. A plate of glass, as a lid to the aquarium, raised about 
half an inch above its upper edge, so as to allow a passage to the air, and 
the occasional stirring of the water, by agitating the dust, will also prevent 
its accumulation on the surface. Remember that light is the great means 
by which oxygen is generated from plants; and give your aquarium plenty' 
of it. Rut, though your tank must stand in a wfindow which admits plenty 
of light, the blind should be kept down during the heat of the day. Once 
let the w T ater get warm, and your pets are, in all probability, doomed. 
If you find the water-level in your salt water aquarium sinking, you 
must fill up the deficiency by adding fresh water, a very little at a time. 
Do not fear that your aquarium will thereby lose its saline properties. Re¬ 
member that the salt does not evaporate, and that the water drawn by the 
sun out of your tank has been as fresh as that with which you supply its 
want. 
