ORTMANN : THE CliAWFISHES OF THE STATE OF PENNSYLVANIA 351 



Only the two last named subgenera, Faxonius and Bartonius, are found witliin the 

 bijundaries of the state of Pennsylvania, and they are distinguished from the rest b}' 

 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. 

 1 11 the Pennsylvanian species of these two subgenera only the third pereiopods possess 

 a liook (used to take hold of the female) on the ischiopodite. 



The two subgenera are distinguished as follows : 

 Subgenus Faxonius Ortinann. 



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 Baiionius Ortmann. 



Sexual organs of the first pair in the male with two rather short, completely 

 sepai-ated tips. Both tips are strongly recurved, forming with the basal part about 

 a right angle. 



B. Keij to the Boin.stjlvdnian Specie,'^ of the Goms Cdmbarus. 



a'. Sexual organs of male of the Famniits-type. Rostrnm alwaj'S with a margioal spine on each side, and carapace 

 with one or more lateral spines. (River species.) 

 I/. Tips of sexual orjians short, straight, and divergent. Sides of carapace with several lateral spines anterior to, 

 and behind the cervical groove. (Delaware, Susquehanna, and Potom^ic drainages.) 



C. (FajOHiM.1) limo8us (Rafinesque). 

 b". Tips of sexual organs long, almost straight, slightly convergent, or parallel. Sides of carapace with only one 

 spine behind the c- rvical groove, 

 e'. Rostrum with median keel. Sexnal organs of male of first form at anterior margin without prominent 

 angle (shoulder). Annulus ventralis of female flat. (Lake Erie and its drainage.) 



C. {Fii-funiiin) propinqiiiis (iirard. 



c". Rostrum without median keel. Sexual organs of male of first form at nnterior margin with a prominent 



angle (shoulder). Annulus ventralis of female with two tubercles in anterior part. (Ohio drainage 1. 



C. (Faxoniusj obscuru.^ Hagen. C^^l- 

 a' . Sexual organs of male of the Bartonius-type. Rostrum always without marginal spines. Carapace generally 

 without lateral spines, 

 i'. Areola wide. Form of carapace depressed. Color brownish or greenish. (Species of the small streams. ) 



C. (liarUmius) barloni (Fabricius). ff- ^If 

 1) ' ■ Areola narrow or obliterated in the middle. Form of carapace rather eompres-scil. ( Burrowing sjiecies. ) 



c'. Areola narrow. Inner margin of hand generally with only one row of tubercles. Color very bright, of 

 tints anusnal among crawfishes. 

 (/'. Color red. Kostram short and very broad. Outer margin of hand serrated. ( Mountains of southern 



Pennsylvania). C ( /f'iWi/nii/.<) rnra/iHii.'i Erichson. f*"/ 



rf". Color blue. Rostrum shoit and narrower. Outer margin of hand rounde<l, not 8errate<l. (Mills of 



southwestern Pennsylvania. ) C. (Barfo»iiu») iiiononjo/riuiw Ortmann. P. i? ^ 



