34 NEW YORK AQUARIUM NATURE SERIES 



should be considered strictly hothouse pets and handled accord- 

 ingly. 



The temperature of the ordinary living room in winter is 

 too low for young alligations, as they require 80 to 85 degrees for 

 their best development and should not be allowed to drop below 

 75 degrees. Below this temperature they become sluggish and 

 cliilled and refuse to eat. 



The pond and river species of crayfishes are well suited to 

 the small aquarium. Those from the mountain streams and cold 

 springs are harder to keep on account of the difficulty of main- 

 taining a sufficiently low temperature during the warm months. 

 They should not be kept with fish smaller than themselves, for 

 they sometimes make too good use of their large pincers. They 

 should be provided with some sort of a retreat in the form of 

 rockwork or stones under which they can hide part of the time 

 on bright days, as they are more or less nocturnal in habit. Some 

 species wijl climb readily among the water weeds. 



There are numerous aquatic insects which can be kept read- 

 ily and which offer a very attractive field for study. Of those 

 available in the adult stage may be mentioned the hard-shelled 

 water-beetles {Dytiscus, Hydrophilns) and the whirligig beetle. 

 The water-bugs, such as the oarsman and the electric-light bug 

 {Belostoma) are among the commoner and larger of the true 

 bugs. The larvae of the dragon-flies, caddis-flies and the dobson 

 or helgramite are even more interesting and may be kept until 

 they emerge in the adult winged condition. These forms are 

 chiefly carnivorous and if kept together the smaller may disap- 

 pear into the rapacious stomachs of the larger. The dragon-fly 

 larvae are even cannibalistic and unless provided with enough 

 food the larger may devour the smaller, even of the same species. 



Any of the above forms may be readily collected with the 

 aid of a small dip-net. While their study has been chiefly con- 

 fined to the entomologist, they will amply repay the labors of the 

 aquarist. 



The following list of fishes includes some of the exotic spe- 

 cies commonly kept by fanciers. Many of them have no common 

 names. The goldfishes, carps, tenches, ides and orfs are also 

 exotic in origin, but have become domesticated in many places. 



Labyrinthine Fishes from India: Macropodus viridi-aur' 

 cfus (Paradise fish) ; Betta rubra (Red Fighting-fish) ; Betta 

 tnfasciata (Common Fighting-fish) ; Trichogaster lalius (Drawf 

 Gourami) ; T. fasciatus (Striped Gourami), Osphromemis tri- 



