102 ORTMANN — AFFINITIES OF CAMBARUS. [April 13, 
4, Rostrum concave above, smooth. Areola narrower. 
c, Margins of rostrum subparallel. Outer part of sexual organs with two 
terminal teeth, the inner part straight. 
C. (Cambarus) angustatus (Lec, ). 
c, Margins of rostrum convergent. Outer part of sexual organs with 
three terminal teeth, the inner part directed outward. 
C. (Cambarus) leconteit Hag. 
2. Group of C. blandingi (see p. 100). 
a, Eyes rudimentary. Outer part of sexual organs with two terminal teeth. 
C. (Cambarus) acherontis Loennb. 
a, Eyes well developed. Outer part of sexual organs with three terminal teeth. 
6, Sexual organs straight, terminal teeth well developed. 
c, Sexual organs not excavated on outer side near distal end. 
C. (Cambarus) blandingi ( Harl. ) 
¢ Sexual organs excavated on outer side near distal end. 
C. (Cambarus) hay Fax. 
6, Sexual organs curved back distally, terminal teeth minute. 
C. (Cambarus) fallax Hag. 
3. Group of C. clarki (see p. 100). 
a, Rostrum concave above, acumen slightly longer. Shoulder of sexual organs 
slightly developed. C. (Cambarus) clarki Gir. 
a, Rostrum plane above, acumen shorter. Shoulder of sexual organs very promi- 
nent. C. (Cambarus) troglodytes (Lec.). 
4. Group of C. allent (see p. 100). 
a, 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. : 
6, Rostrum concave above. Outer part of sexual organs with one recurved 
terminal tooth; inner part with the terminal spine placed obliquely. 
C. (Cambarus) evermannt Fax. 
6, Rostrum plane above. Outer part of sexual organs with terminal part 
plate-like, covering the inner part, and with two very small teeth. 
c, Chelze bearded on inner margjn. C. (Cambarus) barbatus Fax, 
c, Chelze not bearded on inner margin. 
C. (Cambarus) wiegmanni Er. (?). 
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. wéegmanni is very doubtful, since the 
male sexual organs are unknown. It has been placed with C. dar- 
batus by Hagen and Faxon, but only the external resemblance to 
