46 NORTH AMERICAN 



modification of the sixth segment in the female is not noticeable in 

 some specimens. 



27. S. erythropus Mels. — Form moderately robust. Pubescence ex- 

 ceedingly short and sparse, flue, setiform, and cinereous. Head robust, not 

 twice as wide as long ; iuterocular surface twice as wide as the eye, distinctly 

 excavated, rather coarsely, closely, and evenly punctate, interspaces one- 

 fourth as wide as the punctures, shining ; equally trilobed by the sharply 

 marked, longitudinal sulcations, intermediate surface evenly convex ; ocular 

 lines meeting at one length in advance; antennae long and very slender, 

 longer than width of head, dark piceous-brown, basal joint black, club 

 narrow ; third joint one-third as long again as the fourth, fourth and fifth 

 equal, eighth longer than the ninth, joints of club slender, equal in length, 

 ninth and tenth clavate, last conical ; maxillary palpi long and slender, pale 

 fusco-testaceous throughout. Prothorax very robust, widest at the middle, 

 where it is three-fourths as wide as the head, and slightly narrower than 

 long ; sides thence very feebly convergent posteriorly, and distinctly sinuate ; 

 anterior and posterior margins equal in length, the former much the more 

 arcuate ; surface rather unevenly convex, very closely, somewhat coarsely 

 and unevenly punctate ; canaliculation somewhat obscure, narrow, but dis- 

 tinct, commencing at the middle and extending to within one-fourth the total 

 length of the posterior margin. Elytra at base much narrower than the 

 head, sides moderately divergent posteriorly and feebly arcuate; together 

 broadly and very feebly emarginate posteriorly; suture slightly longer than 

 the pronotum ; surface depressed, coarsely, deeply, and very unevenly 

 sculptured, on a small area near the inner basal angles, the punctures are 

 rounded and isolated, with the interspaces much wider than the punctures, 

 the remainder of the surface is very closely and deviously channeled, the 

 channels being generally short. Abdominal segments decreasing very gradu- 

 ally in width, first narrower than the contiguous elytra ; surface convex, 

 coarsely and closely punctulate anteriorly, finely so' posteriorly ; transverse 

 carinae tricuspid, middle cusps slender and aciculate, lateral rudimentary 

 and expanding at apex, intervals rather strongly sinuate. Legs long and 

 slender, pale piceous-brown ; first joint of posterior tarsi more than twice as 

 long as the secoud, longer than the next three together, second distinctly 

 longer than the third. 



Mule. — Posterior edge of fifth ventral segment strongly emarginate in its 

 middle three-fifths, contiguous surface deeply impressed, floor of impression 

 flat, somewhat uneven, impunctate ; sides nearly parallel, in the form of 

 acute, elevated ridges, which terminate posteriorly in two strong acute teeth 

 projecting over and beyond the emargination ; sixth segment narrowly emar- 

 ginate at the apex, notch much deeper than wide, rounded anteriorly, sides 

 nearly straight, surface unevenly and feebly impressed, and impunctate ; at 

 the anterior portion of the impunctate area, there is an elongated, narrow, 

 and very acute cariniform elevation, rising abruptly from the surface ; seventh 

 segment narrow, evenly emarginate at apex. 



Female. — Sixth segment acutely rounded posteriorly and distinctly bilobed 

 at the apex, cusp minute and rounded, arms widely divergent. 



Length 4.0-4.8 mm. 



