DISTINCTIVE CHARACTERS OF THE CRAYFISH. 239 



pede is strongly serrated and wider in front than behind 

 (fig. 44) ; the nieropodite possesses four or five si)ines 

 in the same region ; and there are one or two spines at 

 the distal end of the carpoj^odite. When straightened 

 out, the niaxillipedes extend as far as, or even beyond, 

 the end of the rostrum. 



The inner or sternal edge of the ischiopodite of the 

 forcejis is serrated ; that of the meropodite i^resents two 

 rows of spines, the inner small and numerous, the outer 

 large and few. There are several strong spines at the 

 anterior end of the outer or tergal face of this joint. The 

 carpopodite has two strong spines on its under or sternal 

 surface, while its sharp inner edge presents many strong 

 spines. Its upper surface is marked by a longitudinal de- 

 pression, and is beset with sharp tubercles. The length 

 of the propodite, from its base to the extremity of 

 the fixed claw of the chela, measures rather more than 

 twice as much as the extreme breadth of its base, the 

 thickness of which is less than a third of this length 

 (fig. 20, p. 93). The external angular process, or fixed 

 claw, is of the same length as the base, or a little shorter. 

 Its inner edge is sharp and spinose, and the outer more 

 rounded and simply tuberculated. U'he apex of the fixed 

 claw is produced into a slightl}- incurved spine. Its 

 inner edge has a sinuous curvature, convex posteriorly, 

 concave anteriorly, and bears a series of rounded tubercles, 

 of which one near the summit of the convexity, and one 

 near the apex of the claw, are the most prominent. 



