106 NORTH AMERICAN 



together with a slight depression at the middle of the base, very deeply, 

 evenly, rather coarsely, and exceedingly closely punctured ; punctures deep, 

 polygonal in outline ; interspaces very narrow, minutely granulate, without 

 lustre. Abdominal segments decreasing regularly and quite rapidly in 

 width, first nearly as wide as the contiguous elytra ; border prominent ; 

 surface finely punctulate, minutely but very distantly granulate, not shin- 

 ing ; transverse carinae 4-cuspid, cusps broad, short, wider at the apices. 

 Under surface of the abdomen piceous-black, paler toward the tip, more 

 lustrous than the upper surface and more finely punctulate. Legs moderate, 

 piceous-black ; first joint of the posterior tarsi one-half as long again as the 

 second, second but slightly longer than the third. 



Male. — Posterior edge of the fifth ventral segment sinuate ; sinus very 

 narrow and feeble ; sixth broadly sinuate at apex, sinus evenly rounded, 

 five times as wide as deep. 



Female. — Sixth segment very broadly and evenly rounded behind. 



Length 2.8-3.1 mm. 



Michigan (Escanaba, Marquette, Grand Ledge, Monroe), 51 ; 

 Topeka, Kansas, 1 ; Pennsylvania, 2. 



One of the most distinct species in the genus by reason of its sculp- 

 ture. The surface under a hand-lens seems absolutely without lustre. 



Subdivision i. 

 Group II. 



The characters of the present group have been sufficiently stated 

 above ; the following diagnostic table will, perhaps, distinguish the 

 species more or less satisfactorily : — 



Transverse carinae of abdomen 4-cuspid. 

 Prothorax canaliculated. 



Longitudinal elevation of interocular surface distinct. 



Prothorax widest distinctly before the middle, somewhat cordate. 

 Small species, 2.7-3.0 mm. ; pubescence rather long and conspicuous. 

 Somewhat slender ; ocular lines close and very convergent. Colo- 

 rado 84. dolosus. 



More robust ; ocular lines distant and almost parallel. California. 



85. villosus. 

 Larger species, 3.8-4.0 mm. 



Pubescence almost completely absent ; elytral punctures small, 

 evenly distributed, and widely isolated. District of Columbia. 



86. sectilifer. 



Pubescence rather long and conspicuous ; elytral punctures large, 



deep, rounded, and often semi-coalescent ...87. IllilleportlS. 



Prothorax widest at the middle. British Columbia ....88. jejllllUS. 



Interocular surface nearly flat; sulcations and longitudinal elevation 



obsolete. 



