Crayfish from New Guinea. 3G7 



same sex, th;oiigliout a large series of the Arru Island 

 form . 



It is to be observed, however, that the measurements 

 given by Dr. Roux show this constancy to be far from 

 absolute, and that there is even some overlapping, as re- 

 gards this character, between C. aruanus and C. lorentzi. 

 if the measurements of the chelse be reduced to the ratio 

 Length : Breadth of chela, we get the following results : — 



C. aruayius ? 2'66 to 3*2. 



S 1-9 to 2'Q><. 



C. lorentzi $ 2-8 *. 



c?_ 2-45 to 2-84. 



C. quadricarinatus $ 4*0. 



C. albertid ? 4-23. 



The specimens now examined, from the Mimika River f, 

 give further evidence of the untrustwortliiness of tiie cliela- 

 form as a specific character. In the males the range of 

 variation exceeds that recorded either for G. aruanus or for 

 C. lorenizi, and while none of the females have chel?e quite 

 so slender as those of C. quadricarinatus or G. alhertisii, 

 some of them help to reduce the gap between these and the 

 forms described by Dr. Roux. 



The following is a list of the specimens, with some of the 

 more important measurements : — 



In seven of the specimens wliich have the rostrum un- 

 injured it has two pairs of lateral spinules, but in one 

 (c^ 85 mm. lengtii) it has two spinules on one side and 

 tliree on the other. It seems clear therefore that no import- 

 ance can be attached to the presence of three pairs of spinules 

 as distinguishing C. alhertisii. 



* From Roux's fig. 5. 



t This locality comes within the range of C. lorentzi as indicated by 

 the stations quoted above. 

 :|: Rostrum broken. 



