THE PRAWNS. 



269 



sition, are in fact the same. But, in the prawn, the abdomen 

 is much larger in proportion to the cephalothorax ; the 



Fig. 71. Palcsmon jamaicensis (about 4 nat. size\ A. female ; 

 B, fifth thoracic appendage of male. 



basal scale, or expodite of the antenna, is much larger ; 

 the external maxilHpedes are longer, and differ less from the 

 succeeding thoracic appendages. The first pair of these, 

 which answers to the forceps of the crayfish, is chelate, 

 but it is very slender ; the second pair, also chelate, is 

 always larger than the first, and is sometimes exceedingly 



