ORTMANN: THE CRAWFISHES OF THE STATE OF PENNSYLVANIA 351 
Only the two last named subgenera, Faxonius and Bartonius, are found within the 
boundaries of the state uf Pennsylvania, and they are distinguished from the rest by 
the shape of the male copulatory organs. ‘The latter consist of two parts, which are 
completely separated at the tips for a shorter or longer distance, and never possess 
any accessory spines. The outer part in the male of the first form, (sexually ripe), 
is almost completely transformed into a horny spine, while the inner remains soft. 
In the Pennsylvanian species of these two subgenera only the third pereiopods possess 
a hook (used to take hold of the female) on the ischiopodite. 
The two subgenera are distinguished as follows: 
Subgenus Faxonius Ortmann. 
Sexual organs of first pair in the male with two shorter or longer completely 
separated tips. Tips straight or gently curved, divergent, parallel, or convergent, 
generally rather slender. 
Subgenus Bartonius Ortmann. 
Sexual organs of the first pair in the male with two rather short, completely 
separated tips. Both tips are strongly recurved, forming with the basal part about 
a right angle. 
B. Key to the Pennsylvanian Species of the Genus Cambarus. 
a’, Sexual organs of male of the Faxonius-type. Rostrum always with a marginal spine on each side, and carapace 
with one or more lateral spines. (River species. ) 
v/. Tips of sexual organs short, straight, and divergent. Sides of carapace with several Jateral spines anterior to, 
and behind the cervical groove. (Delaware, Susquehanna, and Potomac drainages. ) 
C. (Faxonius) limosus (Rafinesque). 
b’. Tips of sexual organs long, almost straight, slightly convergent, or parallel. Sides of carapace with only one 
spine behind the e-rvical groove. 
c’. Rostrum with median keel. Sexual organs of male of first form at anterior margin without prominent 
angle (shoulder). Annulus ventralis of female flat. (Lake Erie and its drainage. ) 
C. ( Faxonius) propinguus Girard. 
c’’, Rostrum without median keel. Sexual organs of male of first form at anterior margin with a prominent 
angle (shoulder). Annulus ventralis of female with two tubercles in anterior part. (Ohio drainage). 
C. ( Faxonius) obscurus Hagen. 
a’ 
. Sexual organs of male of the Bartonius-type. Rostrum always without marginal spines. Carapace generally 
without lateral spines. 
ub’. Areola wide. Form of carapace depressed. Color brownish or greenish. (Species of the small streams. ) 
C. (Bartonius) bartoni (Fabricius). 
4’. Areola narrow or obliterated in the middle. Form of carapace rather compressed. (Burrowing species. ) 
ce’, Areola narrow. Inner margin of hand generally with only one row of tubercles. Color very bright, of 
tints unusual among crawfishes. 
d’, Color red. Rostrum-short and very broad. Outer margin of hand serrated. (Mountains of southern 
Pennsylvania). C. ( Bartonius) carolinus Erichson. 
d’’, Color blue. Rostrum short and narrower. Outer margin of hand rounded, not serrated. (Hills of 
southwestern Pennsylvania. ) C. (Bartonius) monongalensis Ortmann. 
