190 NORTH AMERICAN 



decide upon the proper specific limits. The present species differs 

 from obsoletus only in its more robust form, especially of the protho- 

 rax, and in its coarser punctuation. There seems to be considerable 

 variation in the lustre, the males being more polished than the females. 



34. A. disseiltieilS n. sp. — Form slender, sub-cylindrical. Pubescence 

 moderate ill length, slightly denser on the abdomen, rather sparse, somewhat 

 inconspicuous ; entire surface strongly shining. Head moderate or small, 

 twice as wide as long ; interocular surface twice as wide as the eye, very 

 feebly convex, equally trilobed by the very feeble sulcations ; intermediate 

 surface moderately and nearly evenly convex, narrowly impunctate along the 

 middle ; punctures rather coarse, deeply impressed, rounded, close ; ocular 

 lines meeting at one length in advance ; antennae very slightly longer than 

 the width of head, rather robust, piceo-testaceous at base, becoming dark 

 piceous-brown at tip of club, the latter compact and distinct; third joint 

 slightly more than one-third longer than the fourth ; maxillary palpi very 

 long, slender, piceo-flavate, becoming slightly darker toward tip. Prothorax 

 arcuately and evenly increasing in width to a point nearly two- thirds the 

 length posteriorly, where it is slightly narrower than long ; sides thence 

 feebly convergent and slightly sinuate ; anterior margin slightly shorter and 

 distinctly more arcuate than the posterior; surface nearly evenly convex, 

 very feebly and transversely impressed just behind the apex ; punctures 

 moderate in size, round, rather deeply impressed, very close, evenly distri- 

 buted. Elytra at base as wide as the head; sides parallel, slightly, longer 

 than the width at base, rather strongly arcuate toward the apices ; together 

 broadly, somewhat angularly and moderately emarginate behind ; suture 

 one-fourth longer than the pronotum ; surface rather strongly and narrowly 

 impressed on the suture toward the base, also feebly impressed near each 

 humeral angle ; punctures coarse, nearly evenly distributed, round, deeply 

 impressed, distant by slightly more than their own diameters. Abdominal 

 segments decreasing uniformly and gradually in width, first slightly narrower 

 than the contiguous elytra, cylindrical ; border obsolete except on the first 

 segment ; surface coarsely, closely, deeply, and evenly punctate ; transverse 

 carinae not cusped, unevenly toothed. Legs short, rather slender, piceo- 

 fuscous throughout ; first three joints of the posterior tarsi decreasing uni- 

 formly and rather rapidly in length, first much shorter than the next two 

 together; fifth as long as the first three together; fourth 'joints strongly 

 bilobed. 



Mule. — Unknown. 



Female. — Sixth ventral segment obtusely rounded behind, slightly, but 

 rather acutely produced at the immediate vertex. 



Length 2.7 mm. 



Lake Superior, 1. 



This species in general appearance resembles politulus from Van- 

 couver Island, but is readily distinguished from it by the structure of 

 the prothorax and posterior tarsi, also by that of the interocular sur- 

 face of the head and the maxillary palpi. 



