COLEOPTERA. 6-> 



the width at base, and very feebly arcuate; together somewhat narrowly, 

 roundly, and very strongly emarginate behind; suture one-sixth as long 

 again as the pronotum ; surface somewhat feebly convex, nearly even, ex- 

 ceedingly closely and very irregularly channeled, interspaces very acute. 

 Abdominal segments decreasing uniformly and moderately rapidly in width, 

 first just perceptibly narrower than the contiguous elytra; surface coarsely 

 granulose and lustreless ; margin very strong ; transverse carinae not cusped. 

 Legs rather long and slender, black ; first joint of the posterior tarsi much 

 elongated, two-thirds as long again as the second, and much longer than tin- 

 last, second joint nearly as long as the third and fourth together; tarsi of 

 nearly equal thickness throughout, rather slender. 



Male. — Fifth ventral segment very feebly emarginate in its middle third 

 at apex, emargination evenly rounded and scarcely measurable, contiguous 

 surface feebly and cylindrically impressed throughout anteriorly ; sixth 

 segment sinuate at apex, sinus rather wider and more feebly rounded than 

 the apices, evenly rounded, and about five times as wide as deep; seventh 

 segment triangularly and moderately emarginate at apex, lateral setae well 

 developed. 



Fema le. — Unkn o w n . 



Length 3.0 mm. 



Thurston County, Washington Territory, 1. 



A closer scrutiny reveals the fact that the transverse carinae on 

 some of the segments appear to be very minutely 4-euspid, on others 

 even this sign disappears, and there is nothing to be seen but an 

 irregular denticulation of the carinal edge. This conformation will 

 immediately distinguish the species from several others from the same 

 region ; the latter having the carinae distinctly tricuspid. 



Subdivision B. 



This subdivision contains a very large proportion of the species of 

 division B; they may be resolved for sake of convenience into three 

 arbitrary groups as follows : — 



Length exceeding 2 mm. 



Elytral suture not more than one-third longer than the pronotum I. 



Elytral suture at least one-half longer than the pronotum II. 



Minute species not exceeding 2 mm. in length III. 



Group I. 



We are still confronted in this group by nearly one-half the entire 

 number of species of the genus Stenus, and their tabulation in such 

 a manner as to give a useful and succinct character to each form is 

 almost an impossibility. We may, however, simplify the subject 

 slightly, by the following subgrouping : — 



