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BULLETIN OF THE BUREAU OF FISHERIES 
tory than are many fishes, and they are easily obtainable in any locality. The 
present account gathers the literature relating to the species of crayfishes of these 
States, and gives a certain amount of information based on the author’s studies in 
the field. 
METHODS 
The field work in this investigation extended from March 15 to October 30, 
1922, and from April 15 to October 6, 1923. During that time several areas of 
relatively easy accessibility were studied intensively, while only a few hours or a 
day were devoted to others. It is felt, however, that the records furnish an accurate 
account of the distribution and habits of the genus Cambarus in Nebraska and 
eastern Colorado. 
Occasionally collections were made with a net in open ponds and creeks, though, 
except in the evenings, this method gave only immature specimens. The most 
fruitful though often laborious and certainly not aesthetic method is to dig into a 
burrow that gives evidence of habitation, with the hands or with the aid of a small 
trowel, and capture the animals. Although this method is slow and difficult it 
yields a specimen in almost every instance, and permits a study of the nature of 
the soil in which the burrow is located and of the type of burrow made by each 
species. In addition to this, it permits the collector to work throughout the day, 
as the crayfishes are always to be found in their burrows save in the early morning 
and in the evening, when they are in the water feeding. In the case of the creek 
and river species (as Cambarus propinguus ) a minnow trap was used successfully. 
ACKNOWLEDGMENTS 
An investigation of the crayfishes of Nebraska was first begun at the suggestion 
of Dr. Robert H. Wolcott, chairman of the department of zoology of the University 
of Nebraska, and was later extended to the crayfishes of Colorado through the 
encouragement of Dr. Francis Ramaley, head of the department of biology of the 
University of Colorado. To both of these gentlemen I am greatly indebted for 
their helpful suggestions and for laboratory facilities. I desire also to thank Dr. 
T. D. A. Cockerell, of the University of Colorado, for the loan of literature, which 
was not otherwise available; Dr. A. W. Meyer, of Stanford University, for reading 
the manuscript and for suggestions; Dr. E. B. Powers, now head of the department 
of zoology of the University of Tennessee, for assistance in collecting and for the 
loan of literature; and Gayle Pickwell, of the department of zoology of North- 
western University, for assistance in collecting. 
DESCRIPTION OF SPECIES, WITH KEY TO SUBGENERA AND SPECIES 
The first record of a crayfish from Nebraska is by Faxon (1885a ) — “ one species, 
C. virilis, from Omaha.” Faxon (1898) also reports C. virilis and C. immunis as 
being in the collections of Seth E. Meek in the United States National Museum, 
bearing the locality label of “Blue River, Crete County, Nebr.,” and a specimen of 
C. immunis from South Bend, Case County, Nebr. 
Girard (1854) reported a new species, collected at Fort Pierre, which is in the 
present State of South Dakota and which he named Cambarus nebrascensis. Faxon 
regards this species as the western form of C. diogenes. 
