HARD PARTS OF THE COMMON CRAB. 173 



FIG. 91. Ventral surface of male specimen of Callinectes hastatus. 

 (Drawn from nature by W. K. Brooks.] 



ab. Abdomen. 6. Basipodite. c. Carpopodite. ex. Coxopodite. 

 d. Dactylopodite. ep. Episterna. is. Ischiopodite. m. Meropodite. 

 mp s . Third niaxillipeds. s" 1 s viii . Sterna of thorax. p l p 5 . The five 

 pairs of pereiopods. p. Propodite. 



(i.) An oblong basal joint, or protopodite, which runs 

 backwards and forwards, and carries two long, slender, 

 terminal filaments. 



(ii.) The inner one of these, the endopodite, is attached 

 to the inner margin of the protopodite close to its distal 

 end. 



(iii. ) The outer one, or exopodite, is attached to the outer 

 margin of the protopodite near its proximal end. 



2. Straighten out the abdomen of the female, and notice 

 that its dorsal or external surface is continuous with the 

 carapace, while its soft, internal surface is continuous with 

 the ventral surface of the body. Separate the second 

 abdominal somite, and having cleaned out the soft parts, 

 examine it from one end, and notice : 



(i.) The broad, hard, slightly-arched, dorsal surface, or 

 tergum. 



(ii. ) The two lateral flaps, or pleura, which project from 

 the sides of the tergum, beyond the outline of the ventral 

 surface. 



(iii.) The soft, membraneous, ventral portion, or ster- 

 num, much shorter from side to side than the tergum. 

 Notice the point where the appendage is attached, between 

 the tergum and the sternum. The sternum is usually 

 regarded as consisting of three portions, a median true 

 sternum, with an epistemum on each side, between the 

 true sternum and the base of the limb, but no such divis- 

 ion can be seen in the sternum of the abdominal somite 

 of a crab. 



