182 GEO. n. noRN, m. d. 



of hind tarsi longer than all the others together, stout and arcuate, 

 the second joint longer than the two following (which are equal) 

 together. The prosternum is lobed in front. 

 Occurs in Arizona and New Mexico. 



O. innsculus. Say, (Bolboceras) , Boat. Journ. I., 178; opacus 9 > Lee, Trans. 

 Am. Ent. Soc, 1868, p. 51; americanus, Westw., Trans. Ent. Soc, Lond., Ser. 

 II., 2, p. 66. — Ferruginous brown, becoming paler. Head coarsely punctured, 

 clypeus with double margin, the upper forming an arcuate carina, a feeble 

 transverse carina on the vertex. Thorax sparsely punctured in male, more 

 densely in the female, median line extremely indistinct even at base. Elytra 

 striate, strice punctured moderately closely, intervals moderately convex, irregu- 

 larly tri- or externally biseriately punctured, the punctures detiser in the 

 female; sutural angle rectangular. Body beneath sparsely punctured and 

 hairy. Length .20 — .22 inch; 5 — 5.5 mm. 



I have united opacus with muscidus, although they differ somewhat 

 in the sculpture of the upper surface, for the reason that they both 

 agree in the sculpture of the head, and all the specimens known of the 

 former are female and all of the latter male. The sculpture varies in 

 density in the two males before me. 



Westwood describes the clypeus as biangulate, but the figure shows 

 the ordinary hemihexagonal form of this and several other species. 

 I think there is no doubt of the synonymy. 



Occurs in Michigan, Dakota and Nebraska. 



O. simples, Lee, Proc. Acad., 1854, p. 222; Trans. Am. Ent. Soc, 1868, 

 p. 51. — Resembles the preceding in form but the sculpture is denser, the strise 

 of the elytra less deep and the intervals flatter. The clypeal margin is double, 

 but the upper line is not thickened and it follows the hemihexagonal outline of 

 the margin. Median line of thorax very sliglitly evident at base. Body be- 

 neath sparsely punctured, more densely punctured along the middle of the 

 abdomen. Length .20 — .26 inch; 5 — 6.5 mm. 



Occurs in Colorado, Nevada and New Mexico. 



O. Ulkei, n. sp. — Ferruginous brown, moderately shining. Head moder- 

 ately punctured, clypeal margin double, the upper line not thicker, front not 

 carinate. Thorax moderately densely granulalo-punctate, median line moder- 

 ately deeply impressed at basal third. Elytra finely striate, strise very finely 

 punctured, intervals nearly flat, irregularly triseriately sparsely jjunctured. 

 Body beneath sparsely punctured and pilose. Length .20 inch; 5 mm. 



This species resembles superficially the preceding, and difiers espe- 

 cially in the sexual characters of the male as shown in the table. 

 One specimen, Nevada. Cabinet of Mr. H. Ulke. 



O. biarinata$4, Lee, Trans. Am. Ent. Soc, 1868, p. 61. — Ferruginous or 

 brownish testaceous. Head sparsely punctured, clypeal margin arcuate, double, 

 the upper ridge elevated at each end into a small tubercle ^ or flat 9- Thorax 

 moderately densely puuctato-grauulate, median line distinctly impressed at 



