160 NORTH AMKRICAN 



obtns<^ at tip. Prothorax but slightly narrower than the head, widest at the 

 apex where it is very sliglitly wider than long ; sides very feebly convergent 

 posteriorly, feebly sinuate just behind the middle ; apical and basal angles 

 nearly equally and rather broadly rounded ; apex broadly and evenly arcn- 

 ate, base truncate, feebly sinuate in the middle ; disk rather strongly convex, 

 very slightly more so than tlie head, highly polished and impunctate. Elytra 

 at base as wide as the head and distinctly wider than the contiguous pro- 

 thorax ; sides moderately divergent posteriorly, nearly straight near the 

 humeri, strongly arcuate near the apices, slightly shorter than the basal 

 widtii ; together broadly and just perceptibly emarginate behind ; inner 

 apical angles feebly rounded ; suture and scutellum together nearly one- 

 third longer than the pronotum ; disk highly polished and impunctate, with 

 a slight indication of very faint sutural striae which become stronger and 

 widely divergent at the scutellum. Scutellum transverse, short, triangular. 

 Abdominal segments increasing arcuately and rather gradually in width, 

 lirst slightly wider than the contiguous elytra; border strong, nearly verti- 

 cal, thin, becoming narrower posteriorly, suddenly very strongly convergent 

 on the sixth segment ; surface highly polislied and impunctate. Legs n)ode- 

 rate in length, slender throughout, not clouded with darker tint. 



Mule — Emargination of the sixth segment one-half as long as the edge, 

 strong, broadly angiilate at the bottom, edge scarcely reflexed except toward 

 the ends of the emargination which are produced backward in the form of 

 two long parallel porrected horns, the latter concave on their inner faces, 

 the concavity extending under the emargination ; the horn-like projections 

 are membranous and very thin ; the thin membrane is also broadly and 

 roundly emarginate. Seventh segment deeply impressed in the middle, 

 margins of the impression broadly rounded, not having tliin laminae, im- 

 pression extending without break and with equal intensity to the eighth 

 segment which is acute behind. 



Female. — All the segments normal. 



Length 2,S-3.0 mm. 



Calilorniu and Arizona, 11. 



The above description was taken from Dr. LeConte's type which 

 is a female; the male differs slightly in its larger head, in the absence 

 of the median puncture, and in the slightly shorter elytra ; it also has 

 the anterior angles of the pronotum distinctly more acutely rounded 

 tlian tlie posterior. It also differs in tlie antennae, the basal joint of 

 wliicli is fully as long as the next two together and is much more 

 strongly clubbed. 



The very singular sexual characters of this species are different 

 from tliose of any other in the genus and will identify it at once. 



It will be seen that besides the characters given in the table for 

 separating the species into two divisions according to the size of the 

 head, shape of tiie jjronotiim, and siiape ot the femora, there is a fourth 

 of perhaps more importance tlian any of tliem, viz. : tlie lack of the 



