CRUSTACEA 



165 



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

 of which the crab darts through the water. 



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

 .s, the swimmerets ; a 1? 2 , the antennae ; mxp 3 , the 3rd "jaw foot." 



FIG. IQO.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 



