THE CEPHALOTHORAX. 153 
which lie immediately in front of the hindermost, there 
is a small round aperture for the attachment of the 
Fig. 39.—Astacus fluviatilis.—The cephalothoracic sterna and the endo- 
phragmal system (x 2). A, from beneath; B, from above. a, a’, 
arthrophragms or partitions between the articular cavities for the 
limbs ; ¢.ap, cephalic apodeme ; cf, cervical fold ; cpn. 1, epimeron of 
the antennulary somite; 4, anterior, and fh’, posterior horizontal 
process of endopleurite; 7b, labrum ; m, mesophragm ; mt, meta- 
stoma ; p,paraphragm ; J—XTIV, cephalothoracic sterna; 1—14, 
articular cavities of the cephalothoracic appendages. (The anterior 
+ cephalic sterna are bent downwards in A so as to bring them into 
the same plane with the remaining cephalothoracic sterna; in B 
these sterna are not shown.) * 
