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 inhabiting 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 
Unionide of the same waters, the Cambari are wonderfully rich in species, the evolution 
of specific forms having gone on much more rapidly here than in the regions inhabited by 
their relatives, the Astaci. Within the limits of the United States west of the Rocky 
Mountains, and in Mexico and Cuba, fifty-two species of Cambarus are known, while the 
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, the Gulf States, Mexico, and Cuba; and a northern proy- 
ince, which includes the Atlantic States north of South Carolina, the States of the Missis- 
sippi Valley (in sensw eatenso) north of the Gulf States, and Canada. The southern province 
is characterized by the prevalence of species belonging to Groups I. and II. (C. Blandingit 
and C. advena groups). All of the fifteen species of Group IL, excepting C. pellucidus, are 
found within the limits of this province as defined above. C. pellucidus 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, 
Towa, 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 L, 
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 L, I, and IIL, there are found 
within the limits of the southern province six species* belonging to Group III. (C. Bar- 
tonii group), and nine species} of Group LV. (C. affinis group). Only eight of them, how- 
ever, are restricted to the southern province; and of these eight, three (C. Girardianus, 
Alabamensis, and compressus) are known only from the extreme northwestern corner of 
Alabama, in the Tennessee River basin, while three (C. acuwminatus, latimanus, and Jor- 
dant) chiefly inhabit the upper portions of the river-courses in the mountainous regions 
of the province. @. extraneus and C. spinosus are border species with respect to the two 
provinces, being found in the streams on each side of the Alleghany divide, in South 
Carolina, Georgia, and Tennessee. C. Diogenes, immunis, virilis, and rusticus have their 
populous centres of distribution in the north, although they have extended far southward 
on certain lines. 
In the northern province the species of the third and fourth groups (allies of C. Bar- 
tonit and C. afinis) 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. acuminatus, C. latimanus, C. Diogenes, C. extraneus, C. Girardianus, and C. Jordani. 
t C. immunis, C. Mississippiensis, C. Alabamensis, C. compressus, C. lancifer, C. virilis, C. rusticus, C. spi- 
nosus, and C. forceps. 
