15G NORTH AMERICAN 



emarginate, lateral teeth small, lateral setae strong, surface having a longi- 

 tudinal carina in the middle toward the base. 



Female. — Sixth segment strongly produced at apex, prolongations in the 

 form of a cusp with the point slightly rounded ; seventh very narrow at tip, 

 where it is strongly and triangularly emarginate. Antennae not so distinctly 

 infuscate toward tip as in the male. 



Length (extended) $ , 4.9 mm. ; % , 5.3 mm. 



Wyoming Territory, 2; Marquette, Lake Superior, 1. 



Very closely allied to umbratilis, and differing from that species in 

 the following characters, the comparisons being made from males : — 



In fraternus the antennae are relatively shorter and more robust 

 than in umbratilis, and are more distinctly darker toward tip. 



The maxillary palpi of the former are much longer and more 

 slender than those of the latter, in which the second joint is flat- 

 tened, narrowed rapidly toward the base, uniformly colored through- 

 out, not perceptibly wider in the middle than at the distal extremity, 

 and in which the third joint is much shorter and more strongly flat- 

 tened. 



In the former the abdomen is more minutely punctate above. 



In fraternus the apex of the seventh segment is distinctly emargi- 

 nate at tip, while in umbratilis this segment is rounded behind. 



In form, size, vestiture, and in almost all other characters than 

 those mentioned above, the two species can scarcely be separated, but 

 as these differences, especially that of the sexual modifications in the 

 seventh segment, are unquestionably specific, we can only regard this 

 as a remarkable instance of approximation. 



3. A. siibi !»t ;i ( iSis n. sp.' — Form rather robust. Pubescence moderately 

 long, dense, sub-recumbent, rather coarse, cinereous, conspicuous. Head 

 moderate, robust, much less than twice as wide as long; interocular surface 

 strongly convex, very feebly bisulcate, except posteriorly, where the sulca- 

 tions entirely disappear ; finely and evenly punctate ; punctures round, 

 deeply impressed ; interspaces scarcely as wide as the punctures, granulated, 

 feebly convex ; ocular lines meeting at two lengths in advance; antennae 

 slightly longer than the width of head, somewhat slender, basal joint black, 

 remainder pale reddish-testaceous, club slender; third joint one-half longer 

 than the fourth, fourth and fifth equal, sixth to eighth uniformly and gradu- 

 ally decreasing in length, the latter somewhat narrower than the seventh, 

 joints of club elongated, last two equal in length, tenth somewhat more 

 robust : maxillary palpi fusco-piceous, robust, short, basal joint paler, second 

 and third joints strongly flattened, coarsely setose. Prothorax arcuately, 

 evenly, and very gradually widening to the middle, where it is slightly nar- 

 rower than long ; sides thence xary moderately convergent posteriorly and 

 nearly straight; anterior and posterior margins equal, nearly transverse; 

 surface very feebly swollen near the basal angles, finely and evenly punc- 



