56 KANSAS UNIVERSITY SCIENCE BULLETIN. 



species must be the amount and character of the variation, and 

 the absence of intermediate forms, not in one locality alone, but 

 over the whole area of distribution," 



That the conditions of environment under which the different 

 species of Cambarus are found are very diverse is apparent to 

 any one who is acquainted in a general way with the phys- 

 ical features of different regions in which crayfish are known to 

 occur. A study of these conditions and the adaptation of the 

 animals to them may be expected to yield some interesting re- 

 sults. 



While thoroughly convinced of the importance of an ecological 

 study of the crayfishes, I recognize perfectly that for the ma- 

 jority of species of the genus it is as yet impossible to draw any 

 conclusions at all as to the character of habitat or any adapta- 

 tion to it, but we do know quite definitely in a few cases in 

 what type of locality a given species may be found, and in some 

 cases structural adaptations are very marked, and it is my hope 

 that the arrangement of all the data so far secured in a con- 

 venient form for ecological work will shorten the time till our 

 knowledge of these questions may be much more comprehen- 

 sive than it is at present. 



In the following pages is given, in as condensed a form as 

 has been considered advisable, abstracts of all that has appeared 

 on the habits of the different species, so far as it was regarded 

 as worthy of notice, and a list of all the known localities of the 

 species of Cambarus, with the drainage basin to which they 

 belong. This has been compiled and presented as necessary 

 data for a consideration of the ecological relations of any spe- 

 cies, or group of species. While I feel that with our present 

 knowledge of the subject generalizations are of little value, and 

 have sought to indulge very temperately in conclusions, I have 

 in some cases expressed my opinion as to the significance of 

 the facts observed. The main purpose of the paper, however, 

 is the compiling and recording in an easily accessible form of 

 such biological data as have been secured up to the present time, 

 in the hope that they may be of use to those who have better op- 

 portunities than I for further work along this line. Of some 

 of the imperfections of the paper as it is here presented I am 

 as fully aware as the most of those who may see it, but the 



