58. Tips of first pleopod of male very unequal in length, the inner tip being 



less than one-half the length of the outer tip; Miss, to Ala. and Okla. 

 (Subgenus Faxonella Creaser) 



Orconectes clypeatus (Hay) 

 Tips of first pleopod of male about equal 59. 



59. Blind cave species; Ind., Kentucky and Alabama 



Orconectes pellucidus (Tellkampf) 

 (Includes O. inermis Cope) 

 With functional eyes 60. 



60. With a hook (spine or tubercle) on third segment of third and of fourth 



leg (in males of the first form) ; Missouri 

 Orconectes peruncus (Creaser) 

 With a hook on third segment of third leg of male 61. 



61. Areola linear or partly obliterated; Tenn. south and v/est 62. 

 Not so 66. 



62. Rostrum very long, making the anterior section of the carapace about 



three times as long as the posterior section 

 Orconectes \anc\jer (Hagen) 

 Rostrum shorter 63. 



63. No lateral spines on the rostrum in the adult; Miss. 



Orconectes mississippiensis (Faxon) 

 With lateral spines on the rostrum (one on each side near tip) 64. 



64. First pleopod of male reaching only to third walking leg; basal part of 



first pleopod longer than tips 



Orconectes difficihs (Faxon) 

 First pleopod of male longer, with the basal part about equal to or shorter 

 than tips 65. 



65. Antenna a little shorter than length of animal; basal part of larger claw 



of chela thick 



Orconectes palmeri (Faxon) 

 Antenna a little longer than body; basal part of larger claw of chela thin 

 Orconectes palmeri (Faxon) (var. hngimanus) 



66. Both tips of first pleopod of male curving downwards in the same direc 



tion; with a tuft of hair at the inner base of chela (except in O. corw 



pressus and O. harrisom) 67. 



Tips of first pleopod of male either pointing straight ahead or not curving 



in the same direction 76. 



67. First pleopod of male much thickened, with short, stout tips; chela wide at 



base, with claws gaping; Missouri 



Orconectes harrisoni (Faxon) 

 First pleopod of male deeply split and more slender 68. 



68. Inner claw of chela cut out at base; widely distributed 



Orconectes immunis (Hagen) 

 Not so 69. 



69. Posterior section of carapace a little less than one-half as long as the an- 



terior section; southern states 70. 



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



199 



