WATER-MITES AND THE WATER-BEAR. 285 



There may seem to be but little connection between 

 the water-mites and the water-bear, and still less re- 

 semblance, yet naturalists have cla-ssified them near 

 together. The water-bear (Fig. 192) is a common and 

 peculiar aquatic animal, so closely and so comically 

 resembling a transparent eight-legged microscopic 

 bear that the. observer will know it the first time he 

 sees it; further reference to it is therefore reserved 

 for another page. 



Key to Genera of the Water-mites (Hydrachnidce). 



1. Body colorless, cylindrical, elongated, and trans- 



parent; legs eight, short, with claws; the animal 

 walks slowly and is remotely bear-like in appear- 

 ance. Water-bear {Macrobidtus), i. 



2. Body brightly colored, oval, or spherical; legs 



eight, long; animal swimming actively {a). 



3. Body brightly colored, oval, or spherical; legs 



eight, long; animal walking, never swimming ((?). 

 a. Ventral plate single, cordate, the apex pointing 



forward. Diploddntus, 2. 

 a. Ventral plate single, cordate, the apex rounded, 



pointing backward (^). 



a. Ventral plate double {c). 



b. Posterior coxge on the same side not in contact. 



Hydrdchna, 3. 



c. Posterior coxae on the same side in contact by 



their whole length (d). 

 c. Posterior coxae on the same side in contact only 

 by their internal ends, their outer extremities 

 diverging. Eyldis, 4. 



