Isopoda 229 



have been obtained during the winter from mud drawn up through an 



opening in the ice. If the active forms are not available, they may be 



cultured from egg masses which are often present on submerged stones 



or plants and may even be found in viable form in the dried mud of 



seasonal pools. 



Reference 



For the culture of ostracods see also p. 136. 



CYPRIDAE 



Charles H. Blake, Massachusetts Institute of Technology 



THE usual ostracod of aquaria in the northeast is Cypridopsis vidua. 

 This species may be taken from nearly any neutral or faintly acid 

 pond, even if temporary, but is not likely to be found where the margins 

 are marshy. 



Cypridopsis will persist for many months in fair numbers in any 

 balanced freshwater aquarium. The eggs are laid on almost any solid 

 object and all instars are easily found. If mud is present on the bottom, 

 no other special food appears to be needed. 



Other ostracods may occur for short periods but I have not succeeded 

 in keeping them more than a few weeks. They all require abundant 

 oxygen. There appear to be no records of the reproduction of any 

 marine form in captivity nor do young specimens survive more than one 

 or two molts. 



Reference 



For the culture of Cypris see p. 143. 



Subclass Malacostraca, Order isopoda 



A SUGGESTED IMITATION OF A WOODLAND POOL 



Charles H. Blake, Massachusetts Institute of Technology 



CERTAIN animals live only in the presence of much waterlogged 

 wood and fallen leaves, and in situations in which there are almost 

 no algae. Early in March I brought in a small amount of mud con- 

 taining a high proportion of waterlogged bits of twigs, leaves, etc., and a 

 little sand. The freshwater isopod, Asellus communis, was rather com- 

 mon in the situation where the material was obtained and some speci- 

 mens were included in the gathering. 



An aquarium, about 6" x 18" in floor area, was set up with about %" 

 depth of the mud together with such plants and animals as were present 

 in the original bottom sample and 1" depth of stored aquarium water. 

 The aquarium was covered with a loose-fitting glass plate as a protection 



