Dec, 1914] Schaeffer: North American Onthophagus. 2v»1 



last abdominal segment. This segment is at middle broadly arcuately 

 emarginate in the male and is therefore much narrower at middle than 

 at sides, while the female has the last abdominal segment not emargi- 

 nate at middle and of equal or very nearly equal width throughout. 



O. brcvifrons Horn, which I do not know, is not included in the fol- 

 lowing table, but the description is given at the end of the notes and 

 remarks which follow the table. 



Table of the Species of OiNTHophagus. 



1. Thorax and elytra uniformly black, shining 2 



Thorax and elytra either variable in color or when black, never shining 3 



2. Large species, 10-13 mm., upper cephalic carina of male prolonged into a 



moderate long horn or acute tubercle on each side, lower carina 

 absent ; clypeus different in the two sexes, broad, sides almost straight, 

 anteriorly reflexed and anterior margin truncate at middle in the 

 male ; narrower with sides oblique and anterior margin emarginate 



in the female coproides. 



Smaller species, 6-6.5 nim., upper cephalic carina of male obliterated at 

 middle but on each side visible as a short elevated line; clypeus alike 

 in the two sexes, anterior margin truncate polyphemi. 



3. Prothorax on disk and at sides distinctly granulate^ 4 



Prothorax not granulate but punctate, at least on disk^ 7 



4. Prothorax shining, metallic green ; elytra more or less dark metallic green 



with base and sometimes apex testaceous ; the head of the male has 



the upper carina produced on each side into a slender horn, pro- 



^L thorax produced at middle into a broad process, which is arcuately 



■ emarginate at apex subccnetts. 



■ Prothorax dull 5 



5. Clypeus emarginate at apex, color brownish black, head of male with two, 



rather closely placed, erect horns, lower carina absent. Prothorax 

 scarcely produced at middle, the granules less numerous and smaller 



than in Iiecate velutinus. 



Clypeus not emarginate at apex, either truncate, rounded or more or less 



produced at middle 6 



6. Uniformly dark or brownish black, elytra in some western specimens at 



I apex and sides with one or more small testaceous spots; second and 



following intervals with a confused triseriate punctuation ; upper 

 cephalic carina in male feeble or absent, lower carina distinct ; pro- 

 thoracic process elongate and feebly emarginate at apex with a more 

 or less distinct bidentate process at middle of emargination. . ./recaf^. 

 1 The granules are very distinct in stibccnetis, hecate and guatemalensis, 

 but are finer and rather more sparsely placed in velutinus. 



2 In a few species the thorax at apex at sides and middle has some more 

 or less distinct granules, which, however, do not extend to the disk and base 

 where the thorax is plainly punctured. 



