SMITHSONIAN MISCELLANEOUS COLLECTIONS. 



319 



CIRCULAR OF INQUIEIES 



RELATIVE TO THE 



NATURAL HISTORY OF THE AMERICAN CRAWFISH 

 AND OTHER FRESH WATER CRUSTACEA. 



Smithsonian Institution, 



Washington, D, C, Ilarch 1, 1878. 



The Smithsonian Institution desires to call attention to the im- 

 portance of securing for the National Museum full series of the 

 Crawfish and other fresh-water Crustacea of North America. 



Recognizing the fact that the agency of man has already extermi- 

 nated forms which once inhabited the streams and fresh-water 

 basins of the eastern side of the continent, it perceives the neces- 

 sity for speedy preparation to secure the species belonging to the 

 various faunal areas before they are forever lost to science. 



Many facts have recently been added to the recorded history of 

 the Crawfishes which enable a more exact position to be taken with 

 regard to their origin and affinities. Many more observations, how- 

 ever, will be needed to fill out their history ; and every fact bear- 

 ing upon the subject will be of interest and value. 



The student can no longer be satisfied with a bare designation of 

 the species, but he must admit that each stage of growth has its 

 meaning, and that so has every step in physical advance or diver- 

 gence. 



It should be remarked that the habits of a form may vary accord- 

 ing to environment and attending circumstances. Thus in the 

 crawfish, a species will build chimneys of mud in some localities, 



