COLEOPTERA. 115 



I am not certain as to the female sexual characters, the type being 

 damaged. 



This species is very distinct from canaliculatus; they differ in 

 tarsal structure, in the relative lengths of the prothorax and elytra, 

 and, although the character of the sexual modifications is the same, 

 they differ conspicuously in degree. 



91. S. canaliculatus Gyll. — Form rather robust. Pubescence mode- 

 rate in length, rather coarse, close, sub-recumbent, pale piceo-cinereous. 

 Head large and robust, twice as wide as long ; interocular surface feebly 

 convex, twice as wide as the eye, rather finely, deeply, very closely, and 

 evenly punctate, without a trace of sulcations or longitudinal elevation ; 

 ocular lines meeting at rather more than two lengths in advance ; antennae 

 scarcely as long as the width of head, black, slightly paler at tip, slender, 

 club very moderate ; third joint one-fifth as long again as the fourth, fourth 

 and fifth equal, sixth and seventh equal in length, the latter thicker, eighth 

 oval, very small, narrower than the seventh, joints of club increasing in 

 length, the last two of equal thickness ; maxillary palpi piceous-black, first 

 joint and base of second pale testaceous. Prothorax robust, widest slightly 

 before the middle, where it is three-fourths as wide as the head, and dis- 

 tinctly narrower than long ; sides thence moderately convergent posteriorly 

 and slightly sinuate ; anterior margin very slightly longer than the posterior, 

 equally arcuate ; surface nearly evenly convex, very closely, finely, deeply, 

 and evenly punctate ; canaliculation narrow, equal in width throughout, as 

 long as the pronotum. Elytra at base slightly narrower than the head, and 

 but very slightly wider than the prothorax ; sides moderately divergent 

 posteriorly, slightly longer than the width at base, and feebly arcuate : 

 together broadly. and moderately emarginate behind : suture about equal in 

 length to the pronotum : surface convex, narrowly and feebly impressed along 

 the suture; deeply, closely, and evenly punctate; punctures very seldom 

 coalescing ; interspaces narrow, convex, minutely reticulate. Abdominal 

 segments decreasing uniformly and very gradually in width, first as wide as 

 the contiguous elytra; surface broadly convex; finely, very closely, and 

 evenly punctulate ; transverse carinae 4-cuspid, cusps nearly equal, rather 

 approximate, finely aciculate. Legs moderate, black above, piceous-black 

 beneath ; first joint of the posterior tarsi three-fourths as long again as the 

 second, as long as the fifth, joints two to four decreasing uniformly and 

 rapidly in length, fourth thin and oblique, having long cinereous setae 

 beneath. Body winged. 



Male. — Posterior edge of the fifth ventral segment very feebly emarginate in 

 its middle fourth, emargination evenly rounded and just perceptible ; sixth 

 sinuate at apex, sinus very broad and evenly rounded throughout, about 

 eight times as wide as deep, surface piceous-black. 



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



Length 3.2-3.4 mm. 



Cambridge, Massachusetts, 2; White Fish Point, Lake Superior, 

 2; Lake Superior (locality unknown), 1 ; Grimsby, Ontario, 3. 



