WATER-MITES AND THE WATER-BEAR. 271 



appearance. The skin is sometimes shed in captivity, 

 and is not rarely found as a torn, empty, and colorless 

 net, quite worth examining with a high power. There 

 are some soft-bodied species, but they do not seem to 

 be common. 



The body of both the male and female is truncated 

 at the posterior border, but the male has a 

 peculiar short prolongation projecting from 

 the centre of that margin, as in Fig. 176, the 

 shape of the part varying greatly in the dif- 

 ferent species. The females are the most 

 numerous and most frequently met with, 

 The upper surface or back of both sexes 

 often bears a deep, depressed line, sometimes enclosing 

 a small circular or oval area confined to the posterior 

 extremity, sometimes a large space, including the great- 

 er part of the entire back. From others it may be ab- 

 sent. The eyes are two, black, and separated. The 

 color of the body is very different in the numerous spe- 

 cies. It may be blue, green, yellow, red, or almost any 

 bright tint, either diffused or confined to distinct parts. 

 Thus in one female the centre of the body is brown, the 

 sides blue, and the coxae yellow. In another the body is 

 red, the coeca vermilion. Another, a male, has a bright 

 yellow tail, the centre of the body white, with a blue 

 line near the posterior border, and dark brown coeca. 



A species of Arrenurus with a hard and reticulated 

 surface is not uncommonly captured among Ceratophyl- 

 lura and Myriophyllum in rather shady places which, 



