NivERSiTY Science Bulletin. 



Vol. II, No. 3. 



.JUNE, 1903. 



} Whole Series, 

 i Vol. XII, No. 3. 



AN ECOLOQICAL CATALOGUE OF THE CRAYFISHES BE- 

 LONGING TO THE GENUS CAMBARUS. 



BY .T. ARTHUR HARRIS. 

 With plates I to V. 



INTRODUCTION. 



DURING the last few years, much attention has been given 

 to biological or ecological considerations in both botany 

 and zoology, as one may easily convince himself by turning the 

 pages of but a few volumes of current botanical or zoological 

 journals. Concerning the importance of this work opinions are, 

 naturally, greatly at variance. Some, in their enthusiasm, for- 

 get that ecological observations are valuable only as they con- 

 tribute to our knowledge of the causes of the form and structure 

 of the plant or animal body and the nature of its reactions to 

 the conditions under which it exists, and fully merit the criti- 

 cism of some of the older and more conservative morphologists 

 and systematists, that ecology is a very superficial study. 

 Others assign to the newer phase of scientific investigation its 

 more nearly correct value, in regarding it as a very essential 

 aid to an understanding of form and relationship. One can 

 hardly deny the truth of the suggestion which may be offered 

 by some, that ecologists are "making a mess" of the work they 

 are trying to do, but those who have something of an acquaint- 

 ance with the earlier morphological or taxonomic literature 

 may at least suspect that the "ecological mess" is not the 

 first one which has been made since men began recording their 

 observations on plants and animals. There is in ecological 

 work, and here possibly more than in almost any other field, 

 an unfortunate tendency to build large and beautiful theories 



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