178 A REVISION OF THE ASTACID^. 



that the genus Cambarus once flourished in the rivers of Europe. (See pages 42, 176.) 

 The cave species of the United States belong to the same genus as those inhabitin" the 

 outside waters, but are not closely related to any of them. They may be considered as 

 derived from an ancient outside fauna of that region. (See page 42.) 



VI. The genus Cambarus ranges from Lake Winnipeg to Cuba and Guatemala, 

 from 'New Brunswick to Wyoming Territory (in Mexico to the Pacific Ocean). Like the 

 Unionidte of the same waters, the Cambari are wonderfully ricii in species, the evolution 

 of specific forms having gone on mucli more rapidly here than in the regions inhabited by 

 their relatives, the Astaci. Within the limits of the United States -west of the IJocky 

 Mountains, and in Me.\ico and Cuba, fifty-two species of Cambarus are known, while tiie 

 described Astaci (including the subgenus Cambaroides) of Europe, Asia, and the Western 

 United States number but fourteen species, the chances of discovery of new species through 

 further exploration being greatly in favor of the genus Cambarus. 



With regard to the distribution of the species of Cambarus, the whole territory occupied 

 by them seems to fall into two provinces ; — a southern province, embracing the Atlantic 

 States south of North Carolina, tlie Culf States, Mexico, and Cuba ; and a nortiiern prov- 

 ince, wliich includes tlie Atlantic States north of South Carolina, the States of the Missis- 

 sippi Valley (in sensu extenso) north of the Gulf States, and Canada. The southern province 

 is characterized by tlie prevalence of species belonging to Groups I. and II. (C. Blandingii 

 and C. advcna groups). All of the fifteen species of Group I., excepting C. iKlhicidus, are 

 found within the limits of this province as defined above. C. jiellucidus comes from the 

 caves of Kentucky and Southern Indiana. Five of the six species belonging to Group II. 

 are found in the southern province; the fifth, C. gracilis, is a northern species (Wisconsin, 

 Iowa, Illinois). C. simulans has been found in Texas and to the northward in Kansas. 

 The only two species belonging to Group V. (C. Montezuma; and C. Shufeldtii) are confined 

 to the southern province, in Mexico and Louisiana. One species belonging to Group I., 

 C. Blandingii, extends northward beyond the limits of the southern province as far as 

 New York along the Atlantic coast, and up to Wisconsin in the Mississippi Valley. In 

 both the East and the West, the northern form distinctly differs from the southern. (See 

 page 22.) 



Besides the .species of Cambari belonging to Groups I., II., and III., there are found 

 •within the limits of the soutlieru province six species* belonging to Group III. {C. Bar- 

 tonii group), and nine species f of Group IV. (6'. affinis group). Only eight of them, how- 

 ever, are restricted to the soutliern province ; and of these eight, three (C. Girardianus, 

 Alahamcnsis, and comjiress^is) are known only from the extreme northwestern corner of 

 Alabama, in the Tennessee Eiver basin, while three (C. acuminatus, latimanus, and Jor- 

 dani) chiefly inhabit the upper poi-tions of the river-courses in the mountainous regions 

 of the province. C. e.ttraneus and C. S2nnosus are border species with respect to the two 

 provinces, being found in the streams on each side of the Alleghany divide, in Soutii 

 Carolina, Georgia, and Tennessee. C. Biogenics, immunis, virilis, and rusticus have their 

 populous centres of distribution in the nortli, altliough they have extended far southward 

 on certain lines. 



In the northern province the .species of the tliird and fourtli groups (allies of C. Bar- 

 tonii and C affinis) are the dominant forms, wellnigh to the exclusion of those belong- 

 ing to the first and second groups. Nine species belonging to Group III. and eleven to 



* C. ncHminaliis, C, lalimaiiui, C. Biogenes, C. extraneus, C. GirarfliaiiuK, and C. Jordani. 

 \ C. immmiix, C. Misxixsijipiensis, C. Alahamensis, C. compressus, C. lancifer, C. virilis, C. rusticus, C. sjii- 

 nosus, and C. forceps. 



