140 GEO. H. horn,"m. d. 



protuberance is developed the ceplialic carinae and horns become re^ 

 duced to a minimum, while in the last variety in which the protuber- 

 ance is scarcely larger than in the female, the vertical carina at its 

 extremities becomes elevated into two long slender horns. 



Occurs over the same extent of country with the preceding species. 



O. vellltinuH, n. sp. — Black, subopaque, punctures bearing very short setre. 

 Thorax sparsely punctured, between the punctures extremely finely chagrined. 

 Elytra with sides regularly arcuate not narrowing posteriorly, surfiice verv 

 finely striate, strife very distantly punctured, intervals finely chagrined and 

 irregularly biseriately punctulate. Pygidium opaque very sparsely punctured. 

 Body beneath very sparsely but rather coarsely punctured. Length .:50 inch; 

 7.5 mm. 



Male. — Clypeus nearly semicircular with a broad feeble emargination at 

 middle, surface coarsely punctured. Clypeal carina very feeble. Vertex 

 sparsely punctured, carina very feeble at middle, each end elevated into a 

 moderately long slender horn. Thorax slightly protuberant in front. An- 

 terior tibial spur strongly recurved. 



Female. — Unknown. 



This species recalls some of the varieties of the preceding but its 

 entire aspect is different. Its form is somewhat longer and the elytra 

 have regularly arcuate sides so that their form is nearly circular with 

 the emargination at base. It is probable that further collections may 

 produce forms in which the development more nearly approaches that 

 of the preceding species. 



Occurs in Lower California and Arizona. 



The second section contains those species without any trace of 

 prothoracic protuberance. The males are known by the form of 

 the anterior tibiae and by the smoother head. Two species only 

 are known. 



Margin of clypeus at middle acutely notched tiiberonlirrons. 



Margin of clypeus very feebly truncate at middle pensylvanicus. 



O. tuborculirrons Harold, Coleopterologische Hefte VIII., p. 115; tuber- 

 culatus Zimm., mscpt. — Black, subopaque, surface feebly bronzed and very 

 sparsely pubescent. Clypeus acutely notched at middle. Thorax finely cha- 

 grined, sparsely punctato-granose. Elytra finely striate, surface finely cha- 

 grined, intervals biseriately punctate, punctures alternately placed and each 

 bearing a short hair; base and apex with small paler patches. Body beneath 

 piceous sparsely punctate; legs paler. Pygidium sparsely punctate. Length 

 .14 — .20 inch; 3.5 — 5 mm. 



The sexes of this species do not greatly differ. The margin of the 

 head is moderately reflexed, acutely notched at the middle of the 

 cljpeus, the latter more coarsely punctured in the female. The clypeal 

 carina is short in the female and very nearly obliterated in the male ; 

 the vertical carina is also short divided at middle and formiu'' thus 



