122 ORTMANN — AFFINITIES OF CAMBARUS. [April 13, 
far to the northeast. This species has followed, in its dispersal, 
chiefly the direction of the strike of this mountain chain, and 
reaches now from Tennessee to Maine and New Brunswick. _ East- 
ward, it hardly decends to the Atlantic plain, at any rate it does 
not spread over it, and westward it goes as far as Indiana, always 
preferring smaller streams in mountainous or hilly regions. 
C. bartont possesses several marked varieties, chiefly at the south- 
ern and southwestern extremity of its range, in Kentucky, Ten- 
nessee and northern Georgia; one variety (vodustus) seems to 
follow the northwestern edge of the range of the main species, 
from Ohio through northwestern Pennsylvania to western New 
York (and in Canada). ‘This variety has also been reported from 
Maryland and Virginia, but I doubt that this is actually the same 
thing (see below, p. 135). 
Besides, there are three other species in this section, which are 
closely allied to C. dartont. One of them, C. acuminatus, is found 
in North and South Carolina, at the southeastern edge of the range 
of C. dartoni; the second, C. /atimanus, fringes the southern and 
southwestern extremity of the area of C. dar¢ont in South Carolina, 
northern Georgia, northern Alabama, and central Tennessee ; and 
the third, C. Jongulus, is apparently a form belonging to the high 
mountains, being found in the middle of the southern part of the 
main range of C. darfoni along the highest mountain chains of 
North Carolina, Tennessee, Virginia, and West Virginia. Thus it 
is beyond question, that we can regard these three species as local 
forms of C. dartoni, the one belonging to the high mountains, 
another being its southeastern, the third its southern and south- 
‘western representative. 
While the frst and second sections characterize the earlier stage 
of the distribution of the subgenus, the ¢izrd section expresses its 
advance and dispersal over the eastern mountain system of the 
United States. 
Finally, the fourth section (of C. dtogenes) offers remarkable 
conditions. Two of the species, belonging here (C. carodinus and 
monongalensis) are evidently a little more primitive than the rest. 
C. carolinus seems to possess a wide range within the Appalachian 
system. It is a true mountain form, and is found from northern 
South Carolina to southern Pennsylvania, thus representing the 
same direction of migration as C. dartoni, from southwest to north- 
