128 ENTOMOSTKACA. 



and as respiratory organs (branchial feet). The four 

 species figured are very common. 



Cypris tristridta (PL IX. fig. 34) is found in ponds 

 and ditches. The carapace is bivalve, or has two valves, 

 which are convex and oval ; and it is of a greenish 

 colour, with three irregular dark stripes behind. 

 The superior antennae (a) are jointed and finely fea- 

 thery, the inferior antennae (b) having a tuft or pencil 

 of fine filaments arising from their anterior margin. 

 The eye is single. The animal swims steadily and 

 freely through the water. 



The eggs of Cypris (PL IX. fig. 35) are often found 

 in glasses of water containing the animals. They are 

 rounded or oblong, of a red colour, glued together by 

 an amorphous jelly, and adherent to pieces of stick 

 or the sides of the glass. They are enclosed in a 

 thick shell, which exhibits a cellular appearance in 

 the surface view, and is striated in the side view ; so 

 that the structure of the shell is prismatic, as in that 

 of the oyster. When the eggs escape from the shell, 

 they present the appearance represented in fig. 35 #, 

 the body of the young animal being enclosed in a 

 transparent envelope, one end of which forms a blunt 

 protrusion; there is also a separate slender process 

 enclosing the superior antennae. After a time, the 

 envelope is cast off (fig. 35 b) } when the animal begins 

 its active stage of life. Theeast-ofF envelopes (fig. 35 c), 

 with the protruded portions wrinkled, are often found 

 in the sediment of water containing the animals. 

 The structure of these ova is that of what are called 

 winter ova, which agree with the resting-spores of the 

 lower plants or the Algae. 



Cy clops quadricor'nis (PL IX. fig. 30) is another 

 common species. In this the body is closely sur- 

 rounded by the jointed shell, as in a lobster. The 

 superior antennae (a) are very long and many-jointed, 

 each joint having short bristles arising from it, while 

 the inferior antennae are short and four-jointed. There 



