870 HYMENOPTERA OF AMERICA. [PART I. 



carinas below, terminating in its angles. Thorax not globular, 

 rather elongate, ovate. Scutel convex, parted by a groove; 

 post-scutel not parted. Metathorax rounded, divided by a 

 channel. Abdomen a little more elongate than in Ft. aziecus, 

 the first segment not so short, subangular posteriorly. 



The whole insect densely punctured and clothed with fulvous 

 woolly hair. 



Black. Mandibles, clypeus, the first two joints of the antennas, 

 frontal spot, inner orbits and a large post-ocular band, rufous; 

 the clypeus above and scape beneath, yellow. Prothorax above, 

 two spots or a band on the flanks, tegulae, two lines on the disk 

 of mesothorax, scutel, post-scutel, and two large macula? on the 

 metathorax, rufous. Abdomen rufous, with a central band on 

 the 1st segment, and a triangular part at base of 2d segment, 

 black ; all the segments more or less margined with yellow; anus 

 yellow. Feet ferruginous, black at base; coxae spotted with 

 ferruginous ; tibiae of the two posterior pair covered with small 

 spines. Wings pale fuscous, with violet iridescence. 



Var. This species certainly varies greatly in the distribution 

 of its three colors, the black and yellow being more or less 

 extended. 



Bess, a. cliff. — It differs from 0. aztecus by its coloration and 

 particularly by its thorax, not globular, but ovate, much longer 

 than wide. It is very likely to be a Mexican variety of PL 

 Lewisii Cress. I cannot be sure of this without an examination 

 of the typo. It has the wings more violaceous, not ferruginous 

 along the costa; the disk of mesothorax is adorned with two 

 rufous lines and the abdomen may not be as sessile. 



Hab. Mexico. One ? I caught in the valley of Mexico, on 

 the high plateau. 



3. Pt. Aztecus Sauss. — Validus, niger, termissime pnnctatns ; capite 

 etthorace i'ulvo-lanosis; abdomine ovato ; ore, antennarum basi et pe.li- 

 bus rufis; clypeo flavo, apice grosse punctate, bicarinato, infra medium 

 nigro-bimaculato ; puncto po.~.t-oculari, maculis 2 pronoti, post-scutello 

 et abdominis segmentorum limbo, ilavis; segmentis 1°, 2C utrinqne 

 macula rufa ; alis subinfuscatis, costa basi ferruginea ; tegulis rufis. $> . 

 Pteroehilus aztecus Sauss. Rev. de Zool. XXII, 1870, 141, 35 J . 

 Total length, 1(3 mm. ; wing, 12 mm. 



?. Mandibles large, armed with three lobiform teeth, beside 

 the apical point; their external sides strongly ciliated with 



