26o 



E. A. ANDREWS. 



Both bear a fringe of setae along the external edge. This long 

 line of setae seems to represent what is found upon the edges of 

 the common pleopods and may be regarded as a mark of little 

 specialization or of retention of primitive characters, since in 

 Cambarus it is generally specialized as a local group oj setae, or 

 at most in C. Clarkii, as a less simple line. 



The main features of the endopodite are, however, a shallow 

 groove and a very stout ridge along the posterior face, external 

 to the groove. This ridge ends distally as a swelling that is 

 part of the specialized tip of the organ. More enlarged, Fig. 4, 



FIG. 4. 



the tip shows the rounded head in which the ridge ends, the 

 groove to the left of it and a depression to the right. The actual 

 ending of the organ is a sort of complex edge, flattened from 

 before back. 



On the median side of the groove are two horny points, the 

 shorter posterior, the longer anterior. The posterior is com- 

 parable to the large " spatula " and the anterior to the large 

 " canula " of Cambarus Montezumce. External to the groove is 

 a short, blunt anterior point, comparable to the " ligula " of C. 

 Monte -zumce and a long thin knife edge that is a continuation 01 

 the rounded head of the ridge. The organ appears fitted to open 

 a slit into which sperm might flow from the groove. 



In C. Japonicus the two first stylets lie side by side with diver- 



