178 MEMOIRS ON THE COLEOPTERA 



determinable; the recorded characters are unusually indeterminate, 

 for the descriptions of Dejean seldom betray any lack of clearness or 

 precision, and I have been obliged to select from a number of closely 

 allied forms, one that seems to best fit his definition. Our species 

 are rather more numerous than hitherto supposed but are difficult 

 to differentiate very satisfactorily by description; however, the fol- 

 lowing table may prove of some aid in identification: 



Prothorax transverse, with the side margins more or less broadly reflexo- 

 explanate 2 



Prothorax about as long as wide, more convex and with the side margins 

 only very finely reflexed 17 



2 Body intense black throughout and virtually glabrous, the legs black. 

 Lustre above highly polished throughout, the elytra not in the least 

 alutaceous; head nearly as wide as long, evidently narrower than 

 the prothorax, the eyes large and prominent; palpi and antennae 

 rufo-piceous, the latter slender; front with a few fine sparse punctures, 

 except medially, and some long rugae near the eyes; prothorax fully 

 a third wider than long, the sides rounded anteriorly, moderately 

 Converging, oblique and straight posteriorly to the angles, which 

 are very obtuse but minutely subprominent; base broadly, strongly 

 arcuate, as wide as the slightly less sinuate apex; surface with ex- 

 tremely minute, remote and scarcely visible punctures, becoming 

 more distinct toward the periphery, more broadly toward the basal 

 angles, with a feeble rounded impression at base at about outer 

 fourth, the lateral margins rather broadly concave, the edge reflexed; 

 elytra about a third longer than wide, three-fifths wider than the 

 prothorax, distinctly wider posteriorly than at base, the striae 

 rather fine but impressed, finely and closely punctate, the intervals 

 moderately convex, each with a single irregular series of widely 

 spaced punctures, which are barely visibly larger than those of the 

 striae; scutellar stria long; apices broadly sinuate externally; legs 

 and tarsi black, the tarsi beneath, and the tibiae apically, with nu- 

 merous coarse fulvous hairs; male with two short feeble parallel 

 impressions at the apex of the abdomen. Length (cf) 9.5 mm.; 

 width 3.7 mm. Mexico (Tres Marias, Morelos), Wickham. 



*atrolucens n. sp. 



Body piceous to blackish, sometimes variegated with paler, the legs 

 always pale 3 



3 Head and disk of the prothorax concolorous with the elytra 4 



Head and prothorax throughout paler than the elytra, or at least the 

 major part of the elytra, the latter sometimes pale basally, having 

 only about two setigerous discal punctures situated on the third 

 interval 14 



4 Pronotum with very sparse and rather fine punctures, a little larger 

 and less sparse toward the periphery; elytra with about four setiger- 

 ous punctures on the third interval 5 



Pronotum with coarser punctures, more close-set and generally more 

 even in distribution . 6 



