U. S. NATIONAL MUSEUM 



PROCEEDINGS, VOL. XX PL. LXVI 



Crayfishes. 



Fig. 1. Cambarus montezumoe dugexii. Figs. 3, 4. Cambarus montezumoe occidentalis 



Fig. 2. Cambarus monteziunce arenlatus. 



For explanation of plate see page 693. 



