CEDEMERIDyE OF BOREAL AMERICA. 389 



Thorax distinctly longer than wide, not densely punctured, almost devoid 



of pubescence. gracilis. 



Thorax fully as wide as long. 



Thorax not densely punctured, scarcely pubescent, very distinctly 



narrower posteriorly. cceruleus. 

 Thorax very densely punctured, pubescent, scarcely narrower pos- 

 teriorly, quadricollis. 



Ditylus gracilis Lee. Proc. Phil. Acad., vii, p. 18. 



Form rather more slender than the other species, black, 

 head and thorax submetallic violaceous. Head moder- 

 ately coarsely punctate, the punctures distinctly sepa- 

 rated. Thorax distinctly longer than wide, sides moder- 

 ately arcuate in front, gradually narrower posteriorly, 

 disc feebly depressed at middle posteriorly, pubescence 

 short and inconspicuous, surface submetallic, shining, 

 the punctuation not coarse and well separated. Elytra 

 densely punctulate, opaque, with fine and short pubes- 

 cence, disc finely quadri-costulate. Body beneath slight- 

 ly violaceous, very densely punctulate except on the met- 

 apectus. Length .60-. 80 inch. ; 15-20 mm. 



This species is easily known by its usually slenderer 

 form, narrower and not densely punctate thorax. 



Occurs in Oregon and Washington. 



Ditylus caeruleus Rand, (Upis) Bost. Journ. ii, p. 20. 



Form robust, black, with faint violaceous tinge more 

 evident on the head and thorax. Head moderately 

 coarsely, not closelv punctate. Thorax broader than 

 long, widest one-third from apex, thence obliquely nar- 

 rowed to base, which is narrower than the apex, disc 

 somewhat irregular, a shallow triangular expansion in 

 front, surface moderately coarsely, not densely punctate, 

 slightly shining, with a V-shaped region less punctate. 

 Elytra densely punctate and opaque, with extremely short 

 pubescence, disc quadri-costulate. Body beneath slight- 



