1905 | ORTMANN — AFFINITIES OF CAMBARUS. 118 
a, Margins of rostrum straight, parallel or convergent. Marginal spines and 
acumen not bent upward. 
6, Acumen of rostrum long, marginal spines sharp, margins parallel. Fingers 
of chela long. C. (Faxonius) longidigitus Fax. 
6, Acumen of rostrum short, marginal spines small or absent, margins more 
or less convergent. 
c, Acumen of rostrum not considerably shorter than width of rostrum at 
base; marginal spines small, but present; margins slightly 
convergent ; upper surface slightly concave. Fingers of chelz 
not remarkably long and not emarginate at base. 
d, Sexual organs longer, slightly curved. 
C. (Faxonius) virilis Hag. 
d, Sexual organs shorter, more strongly curved. 
é, Immovable finger bearded at base, chela for the rest with- 
out hairs. C. ( Faxonius) nats Fax. 
é, Immovable finger bearded at base, chela pilose. 
C. (Faxonius) pilosus ay. 
-, Acumen of rostrum considerably shorter than width of rostrum at base ; 
marginal spines generally wanting (rarely present and small); upper 
surface deeply concave; margins strongly convergent. Movable 
finger of chela with a deep emargination at base of inner margin. 
C. (Faxonius) immunis Hag. 
3. Group of C. palmeri (see p. 110). 
a, Rostrum with marginal spines. 
6, Sexual organs long. C. (Faxontus) palmeri Fax. 
6, Sexual organs remarkably short. C. (Faxonius) difficilis Fax. 
a, Rostrum without marginal spines. C. (faxonius) misstssippiensts Fax. 
4. Section of C. lancifer (see p. 110). 
Rostrum very long, without marginal spines. Antennal scale very long. Areola 
obliterated in the middle. Chelz long, subcylindrical. 
C. ( Faxonius) lancifer Hag. 
GEOGRAPHICAL DISTRIBUTION OF THE SUBGENUS FAXONIUS. 
The area occupied by this subgenus is almost entirely continuous ; 
it extends over all of the central parts of the United States, from 
northern Texas to Lake Winnipeg in Canada, and from Kansas to 
the Appalachian Mountains. To the south, it hardly encroaches 
upon the domain of the subgenus Caméarus, being found only in 
the northern parts of Alabama and Georgia. To the North, it 
reaches the Great Lakes, and follows down the St. Lawrence valley. 
Eastward, the Allegheny Mountains apparently form a boundary, 
but at two places it has crossed these mountains, namely in the 
north, where C. “mosus is found in the lowlands and rivers of 
