entom6straca and phyll6poda. 269 



cording to the species, and the color may be green or 

 brown, or whitish and marked with several dusky 

 bands, the latter being our common and abundant 

 species. It may be smooth or entirely covered with 

 fine hairs, or only the free borders may be fringed. 



The shell is never opened wide, but the legs and 

 feathery antennae project from a narrow cleft between 

 the valves, the little animal swimming rapidly by 

 their aid, or creeping about the slide or over the aquatic 

 vegetation. 



CiJ^^'M is reproduced by eggs, but "the mass of eggs, 

 including about twenty-four, is attached by the female 

 to water-plants with the aid of a glutinous secretion, 

 an operation which lasts about twelve hours." 



6. Camptocerchs (Fig. 181). 



The shell is elongated, somewhat quadrangular, 

 transparent, and marked by lines traversing the sur- 

 face lengthwise. The beak is blunt, and usually 

 curved downward, or it may extend slightly away from 

 the body, the head being strongly arched. The teeth 

 on the posterior border (not shown in the figure) are 

 small, and vary froip one to four. The eye is small. 

 The eggs are carried in a brood-cavity. The animal 

 occurs chiefly in lakes and in large ponds. 



Fig. 181.— Camptoc^rcus. Fig. 182.— Chydorus. 



