AMERICAN COLEOPTERA. 237 



10. O. nititlnllis, Grav. Micr. 107; Mon. 186; Er. Staph. 792, etc.; O.rugu- 

 hsns. Say, Tr. Am. Phil. Soc. iv, 460; ed. Lee. ii, 576. 



Middle. Western and Southern States; the only sexual difference 

 is that lueutioned by Erich.son ; the sixth ventral segment is very 

 slightly euiarginate in the % . The synonym is on the authority of 

 Erichson. It seems to me an incorrect determination, but as Say de- 

 scribed his species from Mexico, the question does not concern us at 

 the present time. 



11. O. sobriiiiis, n. sp. — Piceous, less shining than 0. punciatus, much as 

 in 0. nitkliihis ; legs pale. Head sparsely punctured behind, more coarsely 

 at the sides; epistoma subopake, quadrate, depressed, smooth, vertex convex, 

 channeled; frontal and posterior impressions nearly united ; sides rounded be- 

 hind the eyes, which are slightlj' prominent. Prothorax densely and coarsely 

 rugosely punctured, dorsal grooves distinct, middle one limited by two ridges 

 more prominent than usual; lateral impressions broad, shallow. Elytra de- 

 pressed, densely and coarsely aciculate. The other characters as in the two 

 preceding species. Length 2 mm; .08 inch. 



California, two specimens; no sexual differences observed. 



12. O. placiisiniis, n. sp. — Very depressed, fuscous, nearly opake, abdo- 

 men shining. Head densely rugosely punctured behind, front less depressed, 

 nearly sinootli, .'-ubopake; vertex slightly convex, impressed; sides prolonged 

 and rounded behind the eyes, frontal and occipital impressions nearly united. 

 Prothorax very densely rugosely punctured, dorsal grooves obsolete, the middle 

 one and the lateral impression being faintly indicated; sides less rounded than 

 usual; hind angles obtuse, not rounded. Elytra punctured like the prothorax. 

 Dorsal segments smooth, ventral finely and rather densely punctured. Length 

 2.3 mm; .09 inch. 



%. — Sixth ventral segment with a small acute projecting angle at the middle 

 of the posterior edge: eighth segment broadly concave. 



Two specimens found by Mr. II. Ulke, in ants' nests near Wash- 

 ington, D. C, one of which he has kindly placed in my collection. 

 The dull lustre is owing to the closeness of the punctures, and not to 

 the want of polish of the very narrow interspaces. This species bears 

 a strong resemblance to Flacusa of the Aleocharini in form of body, 

 and this superficial likeness is increased by the hind angles of the pro- 

 thorax being more distinct than usual, and the sides less rounded. 



\.'j. O. «Iei»rej*SUS, Grav. Micr. 103; Er. Staph. 796, etc.— '^. Head large, 

 flat, almost wi<ier than the prothorax; sixth ventral segment slightly and 

 broadly emarginate, 



9. — Head somewhat narrower than the prothorax, less flat; Sixth ventral 

 (broken in my specimen, described by Erichson as slightly triangularly pro- 

 longed at the middle). , 



One pair found by me in Indiana. These specimens agree accu- 

 rately with the description given by Erichson, of this common Eu- 



TRANS. AMER. EST. SOC. VI. (32) OCTOBER 1877. 



