350 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 99 



of the head separated from each other by the diameter of the pores, 

 whereas in aeneocupreus^ these pores are separated from each other 

 by from two to three times the diameter of the pores. 



Genus 3IAST0GENIUS Solier 



MASTOGENIUS PERUVIANUS, new species 



Elongate, subcylindrical, strongly shining, glabrous, uniformly 

 dark brown, with a distinct cupreous tinge. 



Head broadly, very deeply depressed in front, with a deep, round 

 fovea in the depression between eyes; surface densely, coarsely, uni- 

 formly punctate, the intervals finely granulose or reticulate; eyes 

 with inner margins nearly parallel to each other. Antenna extending 

 to middle of pronotum, serrate from fourth segment ; second segment 

 short, globose; third segment about twice as long as second and dis- 

 tinctly narrower ; the following segments, short and triangular, except 

 the eleventh, which is oblong, and acute at apex. 



Pronotum regularly convex, about one and one-half times wider 

 than long, narrower at apex than at base; sides nearly parallel or 

 feebly sinuate; posterior angles obtuse; anterior margin and base 

 truncate ; surface densely, coarsely, uniformly punctate, the intervals 

 indistinctly granulose. Scutellum triangular, smooth. 



Elytra strongly convex, as wide as pronotum at base ; sides nearly 

 parallel from humeral angles to middles, arcuately expanded at apical 

 thirds, then arcuately converging to the tips, which are separately 

 broadly subtruncate; humeral angles rectangular; surface deeply, 

 transversely depressed along bases, feebly, broadly depressed along 

 sides behind humeri, very densely, coarsely, uniformly punctate, the 

 intervals smooth. 



Abdomen beneath strongly convex, coarsely, rather sparsely, uni- 

 formly punctate, intervals indistinctly reticulate ; last sternite broadly 

 rounded at apex, and clothed with a few inconspicuous, erect hairs. 

 Prostemum without antennal grooves, coarsely, confluently punctate 

 or rugose. Posterior margin of hind coxal plate straight. 



Length 2.75-3.25 mm., width 1-1.25 mm. 



Type locality. — Caiiete, Peru. 



Types and paratypes. — U.S.N.M. No. 58800. 



Described from six specimens (one type) collected at the type 

 locality, January 13, 1938, by J. E. Wille. 



This species resembles Mastogenius subcyaneus (LeConte), but it 

 differs from that species in being glabrous and uniformly dark brown, 

 with a distinct cupreous tinge, and in having the front of the head 

 deeply depressed at the middle, the sides parallel or feebly sinuate, 

 and the anterior margin truncate, and the elytra more coarsely and 

 uniformly punctured. 



