CRUSTACEA 



173 



abdomen. The first antennae are in this case the largest of all 



the appendages and they help in locomotion ; there is a single 



simple median eye. The female carries 



two egg-sacs, attached one on each side 



of the abdomen (Fig. 109). In these 



the eggs are carried until they hatch. 



Cyclops multiplies with astonishing 



rapidity. Together with Daphnia, it 



forms the staple food of many other 



water-inhabiting creatures. 



Order 3 : Osteacoda. 



Cypris. 



Cypris again is a minute, 

 single-eyed form to be 

 found in ponds. The body is trans- Fig. 109.— C^^cZqps. 

 parent and is enclosed in a bivalved c, Egg-bag. 



carapace, owing to which Cypris was 



at one time confused with the bivalved molluscs. Its jointed 

 appendages, however, indicate its true affinity. 



,ni.eye. 



With the aid of 

 a lens two pairs of 

 unbranched jointed 

 antennae may be 

 distinguished, and 

 — near the hind 

 end of the body — 

 two pairs of short 

 jointed legs which 

 may project beyond 

 the shell. The 

 second pair, how- 

 ever, is usually 

 turned backwards 



and upwai-ds, so that it is covered by the shell though it may 



be visible through it (Fig. 110). 



Sometimes the mouth appendages, too, may be seen, 



though the shell must be removed for all to be visible. 



There is one pair of mandibles and two pairs of maxillae, 



of which the first pair is the larger and bears a branchial plate 



mr\ 



Pig. 110. — Cypris. 



m. eye, Median eye ; anii, ant^, two pairs of antennae ; 

 :innd, mandibles ; mx, maxillae ; li, I2, legs. 



