50 THE AQUAVIVARIUM. 



having shown that in deeper water, probably for 

 want of sufficient aeration, the animal would not 

 live long. By degrees my prisoner became very 

 bold ; and when I held my fingers at the edge of 

 the vessel, he assailed them with promptness and 

 energy. About a year after I had him, I perceived, 

 as I thought, a second crayfish with him ; on exa- 

 mination, I found it to be his old coat, which he 

 had left in a most perfect state. My friend had 

 now lost his heroism, and fluttered about in the 

 greatest agitation. He was quite soft, and every 

 time I entered the room during the next two days 

 he exhibited the wildest terror. On the third he 

 appeared to gain confidence, and ventured to use 

 his nippers, though with some timidity, and he was 

 not yet quite so hard as he had been. In about a 

 week, however, he became bolder than ever ; his 

 weapons were sharper, and he appeared stronger, 

 and a nip from him was no joke. He lived in all 

 about two years." 



The Entomostracous Crustacea are most of them 

 fresh- water ; they are known from the other Crusta- 

 cea by their sessile eyes, and the absence of branchiae, 

 or any organs to supply their place. Dr. Baird's 

 beautiful book on the British forms of these crea- 

 tures, published by the Ray Society, contain coloured 

 illustrations of every species. They are charming 

 objects under the microscope, as their transparent 

 shells permit the whole of their internal structure 

 to be seen through them. There is one species a 

 great rarity, the Cancer stagnalis of Linnaeus, the 

 Chirocephalus diaphanus of recent writers. It is a 

 beautiful transparent Crustacean, swimming upon 

 its back, and exhibiting very elegant movements in 

 the water. It is found in abundance on Blackheath 

 Common, and in the ponds by the road-side which 

 are dried up for a great part of the year. It 



