ENTOMOSTRACA AND PHYLLOPODA. 255 



agining. One female Cyclops has been seen to lay ten 

 times in succession ; but, to be within bounds, the ob- 

 server who made the calculation supposes a single one 

 to lay eight times only, and forty eggs at each time. 

 " At the end of one year this female would have been 

 the progenitor of 4, 442,189,120 young- : that is, near 

 four and a half thousands of millions." 



There are about thirty species of Cyclops, and in all 

 of them there are four antennas, two being long and 

 conspicuous, the other two small, and often carried so 

 that they are invisible unless the Cyclops is turned on 

 its back. 



PHYLLOPODA. 



13. LIMNETIS (Fig. 168). 



The oval or nearly spherical, smooth shell has a well- 

 marked beak, which in some of the species is enor- 

 mous, while in others it is less conspicuous. "When the 

 valves are closed they measure about 

 one-sixth of an inch in length, and 

 have often been mistaken for small 

 fresh-water mollusks of the genus Pi- 



Fig. 16S.-Limn6tis. 



sidium. The eyes are two, but so 

 close together that they often appear to be united ; they 

 are black. The animals swim on the back, as do so 

 many of the Phyllopoda. In the males the two front 

 legs are flattened, and have on the end of each a compli- 

 cated organ called the hand, although it bears the most 

 remote resemblance to the human hand. The eggs are 



