Wii.i.iAMsoN : Cravftsh OK Ai,i.i:( ;i[KN\- County. \) 



great changes took place that drove the life from these seas southward, 

 both forms were widely distrilnited over the two continents'. Then 

 those climatic or other conditions, which have made possible the 

 preservation of so many allied faunal and floral forms in Eastern North 

 .America and Eastern Asia, operated for the development of those 

 characters which are found in the genus Camharus, and the supjiression 

 of the characters of the genus Astaciis in these widely sejjarated 

 regions. 



At the present time Dr. P'axon recognizes about 68 species of 

 CatHbarus in North America, besides a large number of named sub- 

 s|)ecies and varieties. The number of species of the genus Astacus in 

 Western North America is very much smaller. Up to the present 

 time five species of Camhants have been recorded from I'ennsylvania. 

 They are as follows: I. C. bartonii (Fabricius). II. C. dioj^enes 

 (iirard. III. C. affiiiis (Say). IV. C. obsc tints Hagen. \\ C. 

 rtts/icits Girard. The following species are represented in the Car- 

 negie Museum by specimens collected in Allegheny ('ounty during the 

 jiast several years: C. bartonii (Fabricius") ; C. bart. tiii, var. robiisttts 

 Hagen ; C. dio}:!;enes Girard ; C. i/itbiits Faxon : C. prof^iiiqiitts Girard 

 and C. rttstictts Girard. C. bartonii, var. robtisttts, C. propiiiqtttts, and 

 C. ditbius have not hitherto been recorded from the State. In addi- 

 tion to the above 5 si)ecies and one variety, another species, C. viri/is 

 Hagen, is represented in the collection of the Museum. These speci- 

 mens were collected from a lake in Ontario, Canada, by Mr. Geo. 

 H. Clapp. 



In descriptions of crayfish little attention has ever been given to 

 their colors. In the first ])lace there is generally little difference be- 

 tween species in this respect, and in the second place all specimens 

 sooner or later fade, assuming a uniform yellowish or reddish tint.' 



1 The student will find the following works most valuable in his studies of Amer- 

 ican crayfishes. They contain descriptions of all recognized specips : 



I. Monograph of the North American Astacidce, by Dr. H. A. Hagen, Museum of 

 Comparative Zoology, Harvard College, 1870. II. A Revision of the Astacidee, 

 Walter Faxon, Part I. The Genera Cambarus and Astacus, Museum of Comparative 

 Zoology, Harvard College, 1885. HI. Notes on North American Crayfishes, Family 

 Astacidas, by the same author. U. S. National Museum, Vol. XII, pp. 619-634, 

 1890. IV. Observations on the Astacidoe in the U. S. National Museum, and in the 

 Museum of Comparative Zoology, with descriptions of New Species, by the same 

 author. U. S. National Museum, Vol. XX, pp. 643-694, 1S98. V. The Craw 

 fishes of the State of Indiana, by W. P. May. Indiana Department of Geology and 

 Natural .Resources, Twentieth Annual Rt]Jort, \V. S. Blatchley, 1895. 



