AMERICAN COLEOPTERA. 181 



Mentum very feebly impressed and in front only. 

 Posterior tibiae as in biarmatus. 



Posterior femora male with tooth at tip, and a smaller acute tooth 

 ^ near the apical third which may disappear; anterior femora 



usually with an acute tooth at middle. 



Clypeus hemihexagonal, anterior margin not double, a small 

 acute tubercle near the suture; vertex with feeble trans- 

 verse ridge frontalis. 



Mentum shWrt, broader than long, not impressed. 



Mentum broader than long, not emarginate in front, with a transverse 

 arcuate row of bristly hairs, causing the mentum to appear very short, 

 deeply emarginate and serrulate in front. 

 Posterior tibiae as in biarmatus. 



Posterior femora male toothed at tip. 



Clypeus hemihexagonal, margin single; vertex with a short 



moderately elevated transverse carina striatns. 



Mentum broader than long, not narrowed in front, anterior angles 

 broadly rounded, surface not impressed, apex arcuate. . 

 Males unknown. 



Clypeus hemihexagonal, margin single; vertex with an acute 

 moderately elevated tubercle. 



Thorax much shorter than any other species, mandi- 

 bles more prominent, angles of labrum prolonged 

 laterally sparsus. 



Tn the table it will be noticed that certain species are described as 

 having a double clypeal margin while in others it is single. In the 

 former case a distinct margin is seen above that to which the labrum 

 is attached as in Elater. This margin is thickened in tnusculus and 

 forms the anterior ridge of which mention is made. 



Having devoted so much space to the description of the special 

 characters of the species, and the synoptic table containing nearly 

 every character of moment, but little now remains except the bibli- 

 ography and synonymy. 



O. pectoralis, Lee, Trans. Am. Ent. Soc, 1868, p. 51. — Color ferruginous 

 brown. Head roughly sculptured by coarse indistinctly limited punctures. 

 Thorax with rather sp.irsely placed granules (denser in front), each bearing a 

 short hair, median line distinet at base only. Elytra rather deeply striate, 

 striae not closely punctured, intervals slightly convex, irregularly triseriately 

 punctured, each puncture bearing a short seta. Body beneath sparsely but 

 rattier coarsely punctured, sparsely hairy. Pygidium nearly smooth. Length 

 .26 inch ; 6.5 mm.* 



The two specimens before me, both males, have the tip of the 

 elytra distinctly sinuate, the sutural angle dentiform. The first joint 



* The measurements of the present paper are taken from the apical margin 

 of the thorax to the tip of the elytral suture. 



