WATER-MITES AND THE WATER-BEAR. 265 



the plural of coxa, a Latin word meaning the thigh. 

 They are variously shaped and arranged, one coxa seem- 

 ing to cover the end of each leg, or appearing to be the 

 thigh belonging to that leg. They are motionless, how- 

 ever, and are really only elevations of the skin, beneath 

 which the muscles of the legs may be seen in action. 

 In some mites the coxae on each side of the body are 

 arranged in groups of two each, the borders of the two 

 which form the group being in contact either by their 

 whole length, as in Figs. 175, 176, and 177, or only at 

 some single point, as in the posterior group shown in 

 Fig. 174. In Figs. 174, 175, 176, and 177 there are four 

 groups, formed of two coxae each ; in Fig. 173 there are 

 six groups, the anterior alone being formed of two, the 

 two posterior groups on each side being of but one coxa 

 each and separated. Their shape differs widely even in 

 the species of one genus ; their arrangement, however, 

 is constant and important. 



The eight legs are long and jointed, the last joint 

 ending in one or two short claws. The hairs fringing 

 their margins are long and numerous, and are used as 

 aids in swimming. They add a good deal to the beauty 

 of the animal. 



Mites are found in salt as well as in fresh water, but 

 with the marine forms this little book has nothing to 

 do. The fresh-water ones are propagated by means of 

 eggs, which are often seen attached to the stems of 

 aquatic plants or to the lower surface of floating leaves, 

 where the writer has obtained them and had them to 



