81. With a ridge on the rostrum; widely distributed 



Orconectes propinquus (Girard) 

 No ridge on the rostrum; east-central states 



Orconectes propinquus sanhorni (Faxon) 



82. First pleopod of male reaching to the base of the second leg 83. 

 First pleopod of male reaching to the base of the first leg 87. 



83. Chela wide, spotted, lengthwise grcxDved; bony entrance to seminal re' 



ceptacle of female nearly round; Arkansas 

 Orconectes rnenae (Creaser) 

 Not so 84, 



84. Outer tip of first pleopod of male blade-like; Ozark region 



Orconectes luteus (Creaser) 

 Outer tip of first pleopod of male spine-like or setiform 85. 



85. Sides of rostrum almost parallel; outer tip of first pleopod of male taper' 



ing; Tenn. and Georgia 



Orconectes erichsonianns (Fa.xon) 

 Sides of rostrum more definitely converging; outer tip of first pleopod of 

 male uniformly slender throughout; east-central states 86. 



86. Rostrum with a faint ridge; tip not upturned 



Orconectes forceps (Faxon) 

 No ridge on rostrum; tip of rostrum upturned 

 Orconectes rusticus (Girard) 



87. Posterior section of carapace a little less than one-half the anterior section; 



southern states 



Orconectes spinosus (Bundy) 

 Posterior section of carapace one-half or more as long as the anterior sec- 

 tion 88. 



88. Sides of rostrum thickened, converging; Missouri 



Orconectes hylas (Faxon) 

 Sides of rostrum scarcely thickened, parallel 89. 



89. Postorbital and lateral spines of carapace small or absent; with a promin' 



ent ridge on the rostrum; Mo., Colo. 

 Orconectes neglectus (Faxon) 

 With sharp postorbital and lateral spines on the carapace; with an obscure 

 ridge on the rostrum; Ky., Ind. 



Orconectes putnami (Faxon) 



GENERAL REFERENCES 



Faxon, W. 1885. A Revision of the Astacidae. Mem. Museum Comp. Zool., 

 Vol. 10, No. 4. Cambridge. 



Faxon, W. 1898. Observation on the Astacidae, etc. Proc. U. S. Nat. Mu' 

 seum, Vol. 20. 



Faxon, W. 1914. Notes on the Crayfishes in the U. S. National Museum, 

 etc. Mem. Museum Comp. Zool. (Harvard), 40 (8), Pp. 351-427. 



201 



