1905.| ORTMANN — AFFINITIES OF CAMBARUS. 127 
GEOGRAPHICAL’ DISTRIBUTION OF THE SUBGENUS BARTONIUS. 
This subgenus is characteristic for the mountainous regions of 
the east of the United States, that is to say, for the Appalachian 
mountains, but the more highly developed, burrowing species have 
in part descended from the mountains, and spread largely over the 
central portions of this country. The greatest number of species 
is found in the southern extremity of the Appalachian system, and 
there is no question that we have to regard this as the center of 
origin of the subgenus. 
The two cave forms of the frst section are widely separated from 
each other. This indicates, on the one hand, that they are not 
very closely allied, and, on the other hand, the discontinuity thus 
displayed again indicates antiquity. ‘The one, C. hamulatus, is 
found in a cave in eastern Tennessee, that is to say, right in the 
center of origin of the subgenus, while the other one, C. sefosus, 
comes from a cave in Jasper Co., Missouri (in the Ozark region). 
This is very remarkable, and very likely indicates, that the center 
of origin of the subgenus possibly includes the Ozark Mountains, 
west of the Mississippi: this is further suggested by the reported 
presence of C. carodinus in the northeastern part of Indian Terri- 
tory, not far from the locality of C. sefosus (see below). Conse- 
quently, we are to regard C. sefosus as the last remnant of the 
primitive forms of the subgenus surviving in the western extremity 
of the original home. 
We have regarded, morphologically, the second section of the 
subgenus as the most primitive group of it: this view is supported 
by the geographical distribution. C. extraneuws is known from 
northern Alabama, northern Georgia, Tennessee, and Kentucky 
(see below, p. 134); C. jordanit is found in northern Georgia ; 
and C. cornutus in Kentucky (locally, only in Edmonson Co.). 
Thus all the localities are in or near the old center of origin of the 
subgenus. The presence of C. extraneus in the Cumberland and 
Tennessee river drainages, as well as in the Alabama river drain- 
age indicates an old drainage feature, namely the Appalachian 
river (see above, p. 116). 
The ¢hird section presents very interesting conditions, such as we 
have noticed in several groups of the subgenus Faxonius. Here 
we have apparently one widely distributed, typical form, C. darfonz : 
this is found all along the Appalachian mountains and extends very 
