10 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ii4 



medially to receive the pygidium, last segment not narrowed medially 

 in the female. 



Key to the Onthophagus of the United States and Canada 



1. Disc of pronotum tuberculate or simply punctate; setae not flattened if 



present 2 



Disc of pronotum closely, setigerously, annularly punctate, the ringlike 

 punctures separated by less than their diameters; each puncture 

 anteriorly with a distinct tubercle, centrally with a short recumbent 

 flattened yellow seta; Georgia, Florida, and South Africa. 



depressus Harold (p. 126) 



2(1). Disc of pronotum smooth or distinctly punctate, tubercles lacking on 



disc or if present, less than one-half of the diameter of nearest puncture 



in basal area 3 



Disc of pronotum tuberculate; punctures, if present, vague with dia- 

 meters approximately equal to that of the tubercles 33 



3(2). Color uniform, rarely with humeral umbone or entire elytra lighter in 



teneral specimens 4 



Pronotum and elytra decidedly different in color, or elytra bicolored or 



spotted 26 



4(3). Species over 7.5 mm. in length, except rarely in batesi in which the 

 nonsetate, finely punctate shining pronotum will distinguish it from 

 the small western species considered here; species occurring west of 



the Mississippi River 5 



Species under 7.5 mm. in length or, if over 7.5 mm., occurring east of 



the Mississippi River 11 



5(4). Basal half of pronotal disc smooth and minutely punctate or very much 



more finely punctate basally than anteriorly, shiny black or brown. . 6 



Pronotum more or less uniformly punctate except near posterior edge . . 8 



6(5). Lateral margin of pronotum lacking an abrupt angle between anterior 



and posterior pronotal angles 7 



Lateral margin of pronotum with an abrupt angle between anterior 

 and posterior pronotal angles; New Mexico, Colorado, Arizona. 



coproides Horn (p. 14) 

 7(6). Cephalic horns of male united by a sharp carina evenly arcuate down 

 one horn across the front and up the other; female with a low, evenly 

 elevated anterior clypeal carina; Texas to Panama. 



batesi, new species (p. 21) 



Cephalic horns of male not united by a carina across the front; female 



with anterior clypeal carina noticeably higher at middle; Mexico to 



Costa Rica, Hawaii inccnsus Say (p. 24) 



8(5). Punctures of pronotum close and more or less uniform in size, separated 

 by less than their diameters, each with a short black inconspicuous 

 seta; surface dull black, finely alutaceous; Arizona. 



cochisus Brown (p. 18) 

 Large punctures of pronotum usually separated by one or more diam- 

 eters, with or without setae; pronotum alutaceous or smooth and 



shining 9 



9(8). Pronotal punctures, at least laterally, with moderately long setae; 



elytra shining orpheus complex; see couplet 17 



Pronotal punctures, at most, with minute setae; elytra dull, distinctly 

 alutaceous 10 



