AMERICAN COLEOPTERA. 235 



1. O. iiieoliliniH, Er. Staph. 791. — %. Seventh ventral with a prominent 

 middle lutie, wliii-h is truncate at tip. 9- Seventh ventral bisinuate, middle 

 lobe broadly rounded. 



Southern States. Easily known by the shining black color, pro- 

 thorax without grooves, and the bright yellow elytra and legs. 



2. O. !«CHll>tus, Grav. Mon. 191; Say, Tr. Am. Phil. Soc. iv, 4fi0; ed. Lee. 

 ii, 575; Er. Staph. 788, etc.; 0. meerens, Mels. Pr. Ac. Nat. Sc. Phil, ii, 42. — 

 %. Seventh ventral with two deep narrow incisions; middle lobe broad, trun- 

 cate, feebly impressed, not longer than the side lobes. Eighth ventral broadly 

 concave. 



Middle, Southern and Western States, and Vancouver's Island. 



Also in Europe. 



3. O. riiffosiis, Er. Col. March, 588; Staph. 786, etc.; Staphi/Iirms rug. Fabr. 

 Syst. Ent. 207, etc.; 0. rugulosus, J Harris, Tr. Hartford Nat. Hist. Soc. 49; 

 O. basalis, Mels. Pr. Ac. Nat. Sc. Phila. ii, 41. — %. Fifth ventral segment with 

 an elevated tubercle at the middle of the hind margin. Seventh ventral deeply 

 and broadly trilobed. 



Canada, Massachusetts and Pennsylvania. Also in Europe. 



4. O. niger, n. sj). — Narrower ajid less depressed than usual, black, shin- 

 ing, legs blackish-brown. Head ovate, nearly as wide as the prothorax, wider 

 behind the eyes, which are very small, and not prominent; surface punctured, 

 front slightly convex, frontal suture entirely wanting; antennal ridges short, 

 obtuse; vertex obsoletely channeled, occipital impressions wanti-ng. Prothorax 

 twice as wide as long, sides rounded, feebly crenulate, hind angles rounded; 

 surface strongly not densely punctured, dorsal grooves deep, straight. Elytra 

 not longer than the prothorax, strongly punctured. Dorsal and ventral seg- 

 ments sparsely punctulate. Length 2.5 — 4.3 mm; .10 — .17 inch. 



%. — Sixth ventral segment with a small tubercle at the middle, and two 

 nearly confluent very small cusps on the hind margin. Seventh ventral bi- 

 sinuate, middle lobe broad, not longer than the lateral lobes. Eighth ventral 

 not impressed 



9. — Seventh ventral strongly bisinuate, middle lobe rounded, longer than 

 the lateral lobes. 



San Francisco, Cala. ; three specimens. British Columbia, one 

 specimen. This last is of small size, piceous, with the elytra paler; 

 the base of the antennae and legs are testaceous. 



6. O. pensylvanicus, Er. Staph. 792. — %. Seventh ventral segment 

 slightly tuberculate, near tiie hind margin bisinuate, middle lobe scarcely 

 longer, truncate and ernarginate at tip. Head larger than in the 9> and more 

 quadrate behind the eyes. 



Middle and Southern States abundant. 



6. O. ruiicipciinis, Mann. Bull. Mosc. 1843, ii, 233.— 'J,. Seventh ventral 

 with two deep incisions, middle lobe short and broad, truncate at tip. Eighth 

 with deep medial groove. 9- Seventh ventral feebly prominent and retuse at 

 the middle of the hind margin. Eighth slightly concave. 



