AMERICAN COLEOPTERA. 103 



I have tried to find a general character that would serve to separate 

 the species inhabiting the Sierra Nevada from the coast species with- 

 out complete success. Usually, however, the stouter antennse, first 

 described by Crotch in 'sequoiarum, and the absence of wrinkles at 

 the median part of the front, mentioned by Casey, characterize the 

 Sierra species. 



Apparently all the Californiau Omus are related to Aiidouinii and 

 the most northern species, ambiguus, is the closest to it ; while the 

 most southern representative of the genus, Icevis, is the farthest re- 

 moved from it. On account of the great similarity of the species, I 

 have not written a complete description of each, but simply a brief 

 summary of the characters by which each may be known. 



SUMMARY OF CHARACTERISTICS. 



O. Dejeani. — Elytrafoveate; 15-21 mm.; lateral margins of thorax obliter- 

 ated behind ; tlioracic margin reflexed ; lahrum deeply hisinuate; head wrinkled 

 all over, impressions oblique; thorax wrinkled all over, widest behind tlie apex, 

 arcuately convergent to base; elytra elliptical, punctate and foveate. 



O. Ciiliforniciis. — Elytra not foveate; 14-17 mm. ; thorax deeply wrinkled, 

 highly polished ; lateral margin of thorax fine and but slightly reflexed, attaining 

 the basal margin ; elytra moderately coarsely punctured ; thorax narrowed behind ; 

 labrnra bisinuate, the median lobe more prominent than the sides; sides of thorax 

 feebly arcuate behind the middle, convergent from the apex ; head wrinkled all 

 over; elytra elliptical, widest at middle, antennae slender. 



O. sculptilis. — Same as preceding, except sides of thorax are strongly 

 rounded behind the middle, labrum nearly truncate, the median lobe very feeble 

 and broadly rounded. 



O. Edwardsii. — Elytra not foveate ; 14-18 mm. ; thorax smoother and less 

 deeply wrinkled, but without any smooth space at centre; sides of thorax con- 

 verging in nearly straight lines to the base; lateral margin of thorax distinctly 

 reflexed, obliterated behind ; labrum bisinuate at apex, the median lobe broadly 

 rounded and moderately advanced ; head with the middle of the front sometimes 

 free of wrinkles, simply punctate, or smooth ; elytra oblong oval, sides feebly 

 arcuate, widest at middle, antennae stout. 



O. montaniis. — Same as preceding, but with still narrower elytra and dif- 

 ferent labrum : deeply bisinuate, the median lobe more prominent with its apex 

 transversely truncate. 



O. Iiigiibris differs, if at all, by the less reflexed thoracic margin, labrum as 

 in montanns, body rather stout. 



O. liecontei.— Elytra not foveate; the thorax smoother and less deeply 

 wrinkled, but without any smooth space at centre; 15-16 mm.; sides of thorax 



TRANS. AM. ENT. SOC, XXVIII. MARCH, 1902. 



