CRUSTACEA 



165 



hairs, so that they form swimming paddles, by the movement 

 of which the crab darts through the water. 



ai a^ 



FlQ. 99. — Portunus, from below, with the abdomen pulled down to expose 

 s, the swimraerets ; %, o^, the autennae ; nixpg, the 3rd "jaw foot." 



Fig. 100. — Zooea Larva 



of Crab. 



(Much enlarged.) 



Fig. ,101. — Megalopa Larva of a Crab. 

 (Much enlarged.) 



The abdominal appendages or swimmerets, having lost 

 their primary function of aiding in locomotion, are much 



