172 NORTH AMERICAN 



Male. — Posterior edge of the third ventral segment just visibly emarginate 

 in the middle sixth, emargination evenly rounded, not measurable, contigu- 

 ous edge distinctly and narrowly beveled ; fourth segment emarginate in the 

 middle sixth at apex, emargination rounded, ten to twelve times as wide as 

 deep, terminated laterally by rounded prominences, contiguous surface im- 

 pressed for a short distance anteriorly; fifth scarcely perceptibly modified ; 

 sixth deeply and broadly incised at apex, incisure occupying nearly the 

 entire tip, anterior angle narrowly rounded, sides straight, about twice as 

 wide as deep ; seventh segment very large and prominent, rounded behind, 

 lateral spinous setae short and robust. 



Female. — Sixth segment rather narrow, acutely angulate at apex, sides of 

 angle nearly straight ; seventh rather narrow, bilobed at tip. Third tarsal 

 joints almost as strongly bilobed as the fourth. Posterior femora not as 

 irregularly swollen in the middle as in the male ; smaller in size. 



Length 4.1 9-5.2 % mm. 



Tenino, Washington Territory, 4; California, 1. 



The specimen from California agrees very well with the male 

 from Tenino, but has the tarsi and palpi paler, and the fifth segment 

 broadly, roundly, and quite appreciably emarginate behind ; the in- 

 cisure of the sixth segment is slightly smaller but similarly shaped. 



The very large seventh segment in the male, and the great dis- 

 parity in the sizes of the male and female, as well as the very large 

 and prominent abdomen, in which the first segment is as wide as the 

 contiguous elytra, are distinguishing features of this species. It must 

 be considered in some respects as one of the aberrant species of the 

 genus. 



The tarsal claw is figured on the plate, fig. 10. 



18. A. patens n. sp. — Form as in pollens. Pubescence moderate in 

 length, dense, semi-erect, coarse, cinereous, conspicuous. Head robust, 

 scarcely twice as wide as long; labruui very prominent and broad; inter- 

 ocular surface two and one -half times as wide as the eye, moderately convex ; 

 sulcations narrow and rather feeble ; intermediate surface broadly convex ; 

 punctures rather large, deeply impressed, round, distant by much less than 

 their own widths in the convex portions, confused in the sulcations ; ocular 

 lines very convergent, meeting at less than one-half a length in front of the 

 labrum ; antennae short and robust, scarcely longer than the width of head, 

 basal joint black, remainder dark brownish-testaceous, club slightly darker; 

 third joint one-half longer than the fourth, not as long as the next two 

 together, seventh much longer and slightly more robust than the eisrhth, 

 tenth more robust than the eleventh ; maxillary palpi short, very robust, 

 basal joint rather slender, testaceous, second and third dark piceous, second 

 joint slightly bent, flattened. Prothorax distinctly longer than wide ; base 

 and apex equal in length, nearly transverse ; sides arcuate, most strongly 

 so just behind the apical angles, nearly straight toward the base ; surface 

 obliquely tuberculate near each basal angle, very feebly swollen on each side 



