208 CR USTA CEA. PART in. 



wards. The mouth has no foot-jaws, and there are 

 only two pairs of feet. Only one pair is seen in the fe- 

 male, for the other pair is bent upwards to support the 

 egg sacs. The Cypris attaches her eggs to the leaves 

 of aquatic plants by a greenish fibre. Not more than 

 twenty or thirty eggs are deposited by one individual, 

 while the heaps contain several hundreds ; so many fe- 

 males contribute to form one heap. The young are 

 hatched in the form of their parent in about four days 

 and a half. As the pools dry up, the Cyprides bury 

 themselves in the sand or mud at the bottom ; if that 



Fig. 152. Section of Daphnia pulex. 



remain moist they survive, if it becomes dry they perish ; 

 but the eggs remain dormant till the return of rain, 

 when they are hatched, and the surface of the water 

 is soon crowded with a swarm of young Cyprides. 



The Cladocera is the first order of the gill-footed 

 Crustacea : their body is defended by a bivalve carapace ; 

 they have from four to six gill-footed limbs, one com- 

 pound eye, and two pairs of antennae, one pair of which 

 is large and adapted for swimming. The Daphnia pulex, 

 or Arborescent Water-flea, of which fig. 152 is a sec- 

 tion, is a common form of this tribe. It is very abundant 



