XXV.-THE CRUSTACEA OF THE FRESH WATERS OF THE 

 UNITED STATES. 



By Sidney I. Smith. 



A— SY^n'OPSIS of the HIGHER FRESH-WATER CRUSTACEA 

 OF THE NORTHERN UNITED STATES. 



The following synopsis is intended to include all the species of deca- 

 pod and tetradecapod Crustacea known to inhabit tlie fresh waters of 

 the Northern United States east of the Mississippi River. It has been 

 limited to this particular region, because there has been at hand no 

 material of any importance from other parts of the country, and because 

 very few species have been described from localities outside of the region 

 included. I should, perhaps, except from this statement the numerous 

 species of Astacidw, but these have been so recently monographed by 

 Professor Hagen that it seems needless to repeat an account of them 

 here. The fresh-water Crustacea are of great economic importance as 

 food for very many, if not all, our fresh- water food-fishes ; and on this 

 account, as well as for purely scientific reasons, I hope this imperfect 

 synopsis will be of service to all those interested in the subject, and 

 trust it will hasten the preparation of a more complete work, including 

 all the species of the United States. 



I am indebted to Mr. Oscar Harger for the descriptions of the species 

 of Asellus and Asellopsis. 



MACRURA. 



Family Astacid^. 



The following list of the species of this family I have compiled largely 

 from Dr. Hagen's most valuable work,* to which the reader is referred 

 for the full account of the species. The crawfishes of all the eastern 

 part of the United States belong to the genus Camharus, but the species 

 appear to be quite numerous, and are difficult to distinguish without 

 careful study. 



Cambarus acutus Girard. 



Proceecliugs Academj' Nat. Sci. Philadelphia, vol. vi, p. 91, 1333 ; Hagen, op. cit, 

 p. 3;"), pi. 1, tigs. 1-5 ; pi. 2, figs. 106-127 ; pi. 3, figs. 143, 144. 



This species, one of the largest of our crawfishes, has an extensive 



* Illustrated Catalogue Museum Couip. Zool., No. 3 ; Monograph of the North Ameri- 

 can Astacidic, 1870. 



