CRAYFISHES OF NEBRASKA AND EASTERN COLORADO 
89 
The previous records of the Colorado species are no more abundant. In the 
collections of Seth E. Meek, mentioned by Faxon (1885a and 1898), is a specimen 
of C. diogenes bearing the label " Clear Lake, Colorado.” This is probably Clear 
Lake in Lake County, west of Denver, as the other locality by that name is in San 
Juan County in the more arid Southwest. 
Harris (1903) reports a specimen of C. diogenes from the St. Yrain River near 
Boulder, Colo. Ortmann (1906) says "Prof. T. D. A. Cockerell has sent me for 
examination a young male, collected October 7, 1905, in a small stream near 
Boulder.” This specimen was also G. diogenes. During 1912 and 1913 Dr. Max 
M. Ellis made collections at Boulder and in other parts of Colorado while working 
on the "Fishes of Colorado,” but he did not publish his records. These records 
were placed at my disposal by Dr. Francis Ramaley. 
While the previous records give but one species for Colorado and two valid 
species for Nebraska, the present investigation has given eight species for the two 
States, two of these being found only in Nebraska, two only in Colorado, and 
four being common to both States. 
According to Ortmann (1906, p. 407), the genus Cambarus is divided into 
four subgenera. Three of these are represented in Colorado and two in Nebraska. 
In the following key and description of species the male of Form I is used; 
that is, the condition of the adult male before the autumn molt has taken place. 
KEY TO THE SPECIES 
a. First pair of abdominal appendages of male short, truncate at tip, outer part ending 
in one to three horny teeth, inner part terminated by acute spine. Hooks present 
on third periopod of male Subgenus Cambarus (sens, strict.) Ortmann. 
Represented by one species. Outer half of first pleopod of male with two terminal 
teeth, both alike; shoulder on anterior margin of pleopod. Rostrum without mar- 
ginal teeth C. ( Cambarus ) simulans Faxon. 
aa. First pair of abdominal appendages of male generally slender, each division of the 
appendage bearing a more or less elongate spine Subgenus Faxonius Ortmann. 
b. Rostrum with median keel. 
c. First abdominal appendages of male reaching to third periopod; rostral keel often 
indistinct C. ( Faxonius ) propinquus Girard. 
cc. First abdominal appendages of male reaching to the first periopod. Rostrum 
with distinct keel; margins of rostrum subparallel C. ( Faxonius ) neglectus Faxon. 
bb. Rostrum without median keel and without spines. Carapace with lateral spines. 
d. First abdominal appendage of male long and deeply bifid, reaching to base of 
chela; branches slender, the outer branch long, inner branch with spoon- 
shaped tip C. ( Faxonius ) virilis Hagen. 
dd. First abdominal appendage short, with sharply recurving tips. Inner face of 
immovable finger of chela thickly covered with hair. Tufts of hair on second 
periopod C. ( Faxonius ) immunis Hagen. 
bbb. Rostrum without median keel but with marginal spines. Chela and first abdominal 
appendage of male as in C. immunis C. ( Faxonius ) immunis spinirostris Faxon. 
aaa. First abdominal appendage of male short and thick, inner and outer parts each termi- 
nating in only one short and thick, strong^ recurved spine, which is set at right 
angles to long axis of appendage Subgenus (Bartonius) Ortmann. 
e. Inner finger of chela without excision at base; outer finger not bearded. Areola 
obliterated in middle C. ( Bartonius ) diogenes Girard. 
ee. Inner finger of chela with deep excision at base; outer finger bearded. Ex- 
tremity of inner tooth of first abdominal appendage of male long and 
slender. Areola obliterated in middle C. ( Bartonius ) argillicola Faxon. 
