AMERICAN COLEOPlERA. 177 



ReTision of the ITnited States species of OCHOD JEUS and 

 other Genera of Scaraba?i<lje. 



BY GEORGE H. HORN, M. D. 



OCHOD^US, Lep. 

 Havino- had occasion of late to examine the Ocliodse,us of our fauna, 

 I noticed certain characters of very great importance which^appear to 

 have entirely escaped observation. These have afforded me the means 

 of presenting an entirely new synoptic table which will render the 

 recoo-nition of our species much more easy and certain without regard 

 to sex. 



The mentura is described by various authors in a similar manner, 

 Lacordaire writes : Mentuin subtransverse^ a little narroicer anteriorly, 

 notched in front, liguJa moderately promineni and entire. I have ex- 

 amined all our species and one {ferrugineus) foreign, with the follow- 

 ing result. 



0. pectoralis, Lee. — Mentum in the form of a broad wedge with tha 

 base in front, which is concave longitudinally, the tip being emarginate 

 and the sides of the base fimbriate with long hairs. 



O.ferrugineus, Esch. (Siberia), has a similar mentum, but the base 

 of the wedge is concave in every direction, while the free lower edge 

 is more elevated and more arcuate ; it is also emarginate in front and 

 fimbriate. 



0. musculus^ Say. — Mentum as long as wide, narrower in front, tip 

 broadly emarginate, and with a deep longitudinal impression extending 

 from base to apex, deeper in front, fimbriate along the sides. A similar 

 form occurs in simplex and hiarmatus. 



0. Vlkei, n. sp.— The form here is an exaggeration of the preced- 

 ing. The longitudinal impression is very deep, the angles of mentum 

 elevated (when viewed from beneath) and the tip not perceptibly 

 emarginate. The impression is here so deep that the mentum appears 

 very deeply bilobed. The edges are fimbriate. 



0. frontalis, Lee, has a mentum as long as wide, feebly emarginate 

 in front and a feeble longitudinal impression near the front only. 



TRANS. AMER. ENT, SOC. V. (23) MARCH, 1876. 



