164 INTRODUCTION TO ZOOLOGY CHAP. 



August, when each female will produce as many as 160,000 

 eggs ! These are carried by the female on her swimmerets 

 for ten or eleven months, and during this time the trapping 

 of such lobsters (said technically to be " in berry ") is for- 

 bidden by law. 



SHORT-TAILED DECAPOD CRUSTACEA 



Crabs are essentially similar in general struc- 

 ture to lobsters and shrimps, the great difference 

 in their appearance being due to the fact that the abdomen 



FIG. 98. A Swimming Crab (Portumis). 

 (Seen from below.) 



is permanently bent right under the thorax, so that it can 

 only be seen from below (Fig. 98). Moreover, the carapace 

 is very thick and strong, and is widened laterally, so that in 

 most forms its width is greater than its length. The antennae 

 which project forward are relatively small, and the mouth- 

 parts are covered by the broad, flat, third " jaw feet " (maxilli- 

 pedes) ; the " walking legs " are very strong, and the first 

 pair bear very large powerful chelae or pincers. In the 

 Edible Crab (Cancer) and in the Common Shore Crab 

 (Carcinus), the large legs are adapted only for walking, and 

 the crabs move by scuttling sideways at a good pace over 

 the ground. In the Swimming Crab (Portunus), shown in 

 Fig. 98, the last pair of legs is flattened and fringed with 



