102 ORTM ANN — AFFINITIES OF CAMBARUS. 



[April 13, 



b 2 Rostrum concave above, smooth. Areola narrower. 



Cj Margins of rostrum subparallel. Outer part of sexual organs with two 

 terminal teeth, the inner part straight. 



C. (Cambarus) angustatus (Lee). 

 c 2 Margins of rostrum convergent. Outer part of sexual organs with 

 three terminal teeth, the inner part directed outward. 



C. (Cambarus) lecontei Hag. 



2. Group of C. blandingi (see p. 100). 



a x Eyes rudimentary. Outer part of sexual organs with two terminal teeth. 



C. ( Cambarus) acherontis Loennb. 

 a 2 Eyes well developed. Outer part of sexual organs with three terminal teeth. 

 b x Sexual organs straight, terminal teeth well developed. 



c x Sexual organs not excavated on outer side near distal end. 



C. ( Cambarus) blandingi ( Harl. ) 

 c 2 Sexual organs excavated on outer side near distal end. 



C. (Cambarus) hayi Fax. 

 b 2 Sexual organs curved back distally, terminal teeth minute. 



C. (Cambarus) J "alia x Hag. 



3. Group of C. clarki (see p. 100). 



a x Rostrum concave above, acumen slightly longer. Shoulder of sexual organs 

 slightly developed. C. (Cambarus) clarki Gir. 



a 2 Rostrum plane above, acumen shorter. Shoulder of sexual organs very promi- 

 nent. C. (Cambarus) troglodytes (Lee). 



4. Group of C. alleni (see p. 100). 



«j Outer part of sexual organs with one or two terminal teeth ; inner part not 

 longer than the outer. Hooks of fourth pereiopods of male not bituber- 

 culate. 

 b x Rostrum concave above. Outer part of sexual organs with one recurved 

 terminal tooth ; inner part with the terminal spine placed obliquely. 



C. (Cambarus) evermanni Fax. 

 b 2 Rostrum plane above. Outer part of sexual organs with terminal part 

 plate-like, covering the inner part, and with two very small teeth. 

 * c x Chelae bearded on inner margin. C. (Cambarus) barbatus Fax. 



c 2 Chelae not bearded on inner margin. 



C. (Cambarus) wiegmanniYx. (?). 

 a.. Outer part of sexual organs forming at apex a broad, flattened plate, whose an- 

 terior margin is furnished with hairs and one strong seta, the posterior 

 margin of the plate produced anteriorly into a blunt process. Inner part 

 produced into an erect spine, which is much longer than the outer part. 

 Hooks of fourth pereiopods of male bituberculate. 



C. (Cambarus) alleni Fax. 



Note : The position of C. wiegtnanni is very doubtful, since the 

 male sexual organs are unknown. It has been placed with C. bar- 

 batus by Hagen and Faxon, but only the external resemblance to 



