23. Protarsi of male rather strongly dilated, the third joint evidently 

 wider than the fourth though much less than twice as wide; pro- 

 tarsal claws of male more elongate and quite distinctly sinuate; epi- 



pleura in great part blackish or piceous (except nigripalpis.) 24 



Protarsi of male feebly dilated, the third joint scarcely or only just 

 visibly wider than the fourth, the claws slender and only just per- 

 ceptibly sinuate beneath ; epipleura pale 26 



24. Last palpal joint entirely or in great part black; form narrower and 



slightly obovate. (Arctic America and Siberia.) nigripalpis 



Last palpal joint entirely testaceous, or at most a little infuscate api- 

 cally; form broader, size larger 25 



25. Epipleura entirely dark. (Vancouver to South California.) morosus 



Epipleura blackish internally, the outer margin pale. 



Size smaller (less than 7 mm.) ; form more obtusely rounded 



anteriorly. (Oregon.) , ancillus 



Size larger (7 to 8 mm.) ; form more oval. (Rocky Mts. ) ... .obliteratus 



26. Elytral reticulation less fine, the meshes obviously unequal and of 

 irregular form almost throughout, becoming nearly equal only at the 

 extreme apex ; distance between mesocoxal cavities and coxal plates 



equal to or greater than half the length of the latter 27 



Elytral reticulation more minute, the meshes unequal on close exami- 

 nation baso-medially, but becoming nearly equal toward the sides and 

 apex; outer joints of antennae and palpi without or with only faint 

 infuscation 28 



27. Apices of outer joints of antennae, and apical half or more of ter- 

 minal joints of palpi blackish; prosternal process arcuately convex in 



cross section ; form more elongate congener 



Antennae and palpi without appreciable infuscation; prosternal proc- 

 ess narrower and strongly angulate or compresso-carinate ; form a 

 little broader approximatus 



28. Metasternal wings shorter, the distance separating the meso-coxal 

 cavity from the coxal plate less than half the length of the latter; 



prosternal process rather less narrow and less convex discolor 



Metasternal wings longer, the coxal plate distant from the meso-coxal 

 cavity by about half its own length; prosternal process rather nar- 

 rower and more strongly convex inscriptus 



29. Prosternal process arcuately to subangularly convex in cross section 30 



Prosternal process abruptly acutely carinate along the middle 32 



30. Sides of prothorax conspicuously pale; claws of male protarsi larger 



and more strongly sinuate canadensis 



Sides of prothorax not at all or only extremely narrowly and vaguely 

 paler 31 



31. Posterior protarsal claw of the male obtusely subangulate at about 

 one-third from the tip, the anterior claw feebly sinuate on its inner 

 edge; metasternal wings a little broader (in a longitudinal sense.) 



subfuscatus 



Posterior protarsal claw feebly sinuate toward the base, the anterior 



one scarcely so ; metasternal wings a little narrower. 



