58 THE SEA SHORE 



colouring. Some of these stones placed on the bed of the salt- 

 water aquarium would add greatly to the natural appearance, as 

 well as give greater variety to the living objects. Shells bearing 

 the calcareous, snakelike tubes of the common serpula (p. 121), 

 preferably with the living animals enclosed, will also enhance the 

 general appearance and interest of the aquarium. 



In making preparations previous to the introduction of animal 

 life, due regard should be paid to the peculiar requirements of the 

 creatures it is intended to obtain. We have already referred to the 

 advisability of arranging the bed of the tank in such a manner 

 that the water may vary considerably in depth, so that both deep 

 and shallow water may be found by the animals as required, and 

 to the provision of dark holes for crustaceans and other creatures 

 that shun the light. Very fine sand should be provided for 

 shrimps, prawns, and other animals that like to lie on it ; and this 

 sand must be deep in places if it is intended to introduce any of the 

 burrowing molluscs and marine worms. 



The water used may be taken from the sea or be artificially 

 prepared. The former is certainly to be preferred whenever it can 

 be conveniently obtained, and at the present time few will find 

 much difficulty in securing a supply, for not only are we favoured 

 with the means of obtaining any desired quantity by rail at a cheap 

 rate from almost any seaport, but there are companies in various 

 ports who undertake the supply of sea water to any part of the 

 kingdom. If the water is to be conveyed from the coast without 

 the aid of the regular dealers in this commodity, great care must 

 be taken to see that the barrel or other receptacle used for the pur- 

 pose is perfectly clean. Nothing is more convenient than an 

 ordinary beer or wine barrel, but it should be previously cleansed 

 by filling it several times with water not necessarily sea water 

 and allowing each refill to remain in it some time before 

 emptying. This must be repeated as long as the water shows 

 the slightest colouration after standing for some time in the 

 barrel. 



Should any difficulty arise in the way of getting the salt 

 water direct from the sea, it may be made artificially by dis- 

 solving ' sea salt ' in the proper proportion of fresh water, or even 

 by purchasing the different salts contained in the sea sepa- 

 rately, and then adding them to fresh water in proportionate 

 quantities. 



