20 THE BUTTERFLY VIVARIUM. 



This was the discovery of Mr. Warington, the 

 true founder of the Aquarium theory, without which 

 it was found impossible to preserve, for any length 

 of time, either salt or fresh water in a state of purity ; 

 the Periwinkle or Sea Snail performing those func- 

 tions of the scavenger for sea-water which the com- 

 mon Pond Snail does for lakes and rivers. The 

 Trumpet Snail is useful for this purpose, and, with 

 its regularly coiled form, it is a very pretty object ; 

 there is also the beautifulMarsh-shell,Pafo<c?wa Vivi- 

 para, with many others. A few of the graceful little 

 fish popularly called Sticklebacks might be added, 

 to give an appearance of life and movement to the 

 water, and also for the chance of observing their 

 curious instinct in forming a positive nest, in which 

 to deposit their spawn — an almost solitary instance 

 of nest-building among the whole of the fish tribe. 

 Many other objects might be made to vary the 

 water department ; but as in the insect Vivarium 

 they should not form the principal object, I shall not 

 refer to them here, but proceed at once to notice 

 the kinds of insects best suited for rearing in such a 

 receptacle, which I may best do in a brief descrip- 

 tion of the contents of the Vivarium represented in 

 our first Plate. 



In the water, as there indicated, the larvse of 



