NORTH AMERICAN COLEOPTERA. 49 



in Dr. LeConte's collection is to be relied on, and differs from it 

 supeificiuUy in the nature of the elytral sculpture, as well as in the 

 relatively more elongated prothorax. I have not had an op[)ortunity 

 to examine it more minutely. If the two should prove identical, it 

 will be a source of surprise that Haldeman's species should have 

 been suppressed and united with extricata. The above differences 

 are so marked that it is difficult to conceive of their having been 

 overlooked. 



PLATYDEMA. 



P. pernigrillll n. sp. — Form regularly elliptical, elongated, moderately 

 convex, more than twice as long as wide ; glabrous, opaque. Color above 

 deep black, beneath rufous. Head wider than long, somewhat trapezoidal ; 

 anterior margin transverse, angles rounded ; interocular surface nearly flat, 

 punctures throughout very small, round, deeply impressed, very closely 

 crowded, evenly distributed ; antennae slightly shorter than the basal width 

 of pronotum, first four joints reddish-testaceous, joints five to ten black, last 

 joint reddish-testaceous, the outer joints distinctly flattened, joints eight to 

 ten distinctly broader than long ; last joint of the maxillary j^alpi twice as 

 long as wide, as long as the second and third together ; mentura slightly 

 longer than wide, narrowed toward the base, anterior angles broadly rounded, 

 feebly emarginate anteriorly, exposed surface very strongly convex in the 

 midd-^e, the summit of the nearly hemispherical convexity bearing a trans- 

 verse, bilobed, spongy patch ; mandibles very strongly bidentate at tip, teeth 

 very acute. Prothorax at base twice as wide as long; base one-half longer 

 than the apex, transverse and straight at the sides, strongly arcuate in its 

 middle third ; apex broadly and feebly emarginate ; sides evenly and feebly 

 arcuate ; anterior and posterior angles slightly rounded ; disk broadly and 

 evenly convex, narrowly reflexed at the sides, which are narrowly margined, 

 lateral edges acute ; surface most minutely granulate, also evenly and very 

 finely punctulate, punctures very feeble. Scutellum slightly wider than long, 

 acute posteriorly, sides arcuate. Elytra at base as wide as the contiguous 

 pronotum ; sides parallel and moderately arcuate for two-thirds tlieir length 

 from the humeri ; disk three times as long as the pronotum, rather acutely 

 and very evenly rounded behind ; sides narrowly and rather strongly reflexed 

 throughout ; surface punctate, punctures round, rather deep, sub-variolate, 

 arranged in rather distant striae, distance of punctures in the rows equal to 

 about one-third the distance between the latter ; also very finely, evenly, 

 closely, and feebly punctulate ; finally excessively finely granulate. Poste- 

 rior portion of fourth, and anterior portion of the fifth ventral segments 

 having a deep, transverse, and common impressed groove. Legs moderate ; 

 first joint of the posterior tarsi equal to two-fifths the entire length of the 

 latter. Length 6.7 mm. ; width 3.2 mm. 



Arizona (Morrison). 



This*species differs from P. Janus in its much more elongate form; 

 in the color, that oi' jcmtis being usually of a reddish-black above; in 

 Published August, 1884. 4 



