Casey — A Revision of the American Paederini. 45 



arcuate, the base a little narrower than the apex; elytra rather less 

 elongate, distinctly wider and longer than the prothorax, the 

 punctures coarser, deeper and less close-set, partially serial in 

 arrangement toward base especially toward the scutellum ; abdomen as 

 wide as the elytra, otherwise similar. Male with the fifth ventral 

 feebly sinuato-truncate posteriorly, much more feebly sinuate at the 

 middle than in paci/icwni, the notch of the sixth more parallel-sided, 

 nearly as in Paederus, fully twice as deep as wide. Length 8.3 mm.; 



width 1.38 mm. British Columbia yaucouTeri n. var. 



Elytra shorter than the prothorax and usually but little wider, the body 

 more slender and much more parallel, black, the elytra somewhat pice- 

 ous; legs pale, the antennae dasky; head longer than wide, as wide as 

 the elytra, the eyes moderately prominent, the punctures strong, deep, 

 moderately close-set; prothorax more or less distinctly narrower than 

 the head, much longer than wide, the sides feebly convergicg toward 

 base, broadly arcuate especially anteriorly, the punctures rather large, 

 strongly impressed, not very close -set, aggregated as in pacificum, 

 the aggregation along the smooth line usually broadly impressed 

 posteriorly; elytra barely as long as wide, rather depressed, the sides 

 feebly diverging as a rule, the punctures strong and close-set throughout, 

 arranged without order; abdomen as wide as the elytra, finely but 

 strongly, closely punctate. Male with the fifth ventral broadly, feebly 

 sinuate toward the middle, the sixth with an abrupt and very deep tri- 

 angular emargination, not quite twice as deep as wide, its angle broadly 

 rounded; female differing but little from the male in general form, the 

 sixth ventral very broadly, feebly arcuate at tip. Length 8.7 mm.; 

 width 1.28 mm. Southern California and Nevada (Reno) to British 

 Columbia calif oruicum Lee. 



6 — Head inflated posteriorly, the sides behind the eyes parallel and 



distinctly arcuate; pronotum highly polished throughout, never aluta- 



ceous 7 



Head not inflated posteriorly, the sides parallel or nearly so and usually 

 straight for some distance behind the eyes 9 



7 — Male with the apex of the fifth ventral transversely and rectilinearly trun- 



cate, with a minute triangular tooth at the middle. Body moderately 

 stout and convex, polished, black throughout, the legs pale, the antennae 

 dusky; head but slightly longer than wide, equal in width to the elytra< 

 the punctures coarse, deep and well separated; lateral tumid ridge 

 strong; eyes scarcely at all prominent, almost entirely visible from 

 above; neck wide, fully three-fifths as wide as the head; prothorax 

 large, slightly elongate, not very much narrower than the head, parallel, 

 the sides feebly arcuate; punctures rather coarse, impressed and some- 

 what close-set throughout, the median smooth area distinct; elytra but 

 little longer than wide, only slightly wider and longer than the protho- 

 rax, parallel, not very coarsely but deeply, very closely and confusedly 

 punctate; abdomen as wide as the elytra, finely, densely punctate, 

 more minutely but rather less densely so beneath. Male with the flfth 

 ventral unimpressed, the sixth with a large triangular notch much deeper 

 than wide, with the angle flnely acute and the edges broadly and grad- 

 ually beveled, the adjoining surface anteriorly not much modified, nor- 



