ZETHUS. 49 



and shining. Petiole quite lengthened-pediculate ; its elliptical 

 enlargement is globularly swelled above, as high as wide (sub- 

 compressed), having on its posterior extremity above, a large 

 excavation, and on each side a large transverse groove, which 

 compresses the end of the petiole, but without coalescing with the 

 middle groove. Second segment lengthened-pediculate, almost as 

 in the Z. Chicotencatl ; its globular part very flat beneath, and 

 much swelled above from its base ; its first posterior border a 

 little sinuous, preceded in the middle by a vague depression. — its 

 second border not being at all reflected. Margin of the third 

 segment formed in the same way, but the first border more 

 sinuous. Head coarsely punctured; the face cribrose, but the 

 vertical inflation very much less. Thorax cribrose with sunken 

 points, except the metathorax. Petiole and abdomen smooth 

 and shining, while the last is very finely punctured. The third 

 segment punctured. 



Insect black, garnished with a gray or slightly golden pile; two 

 spots on the face, one behind each eye ; margin of the prothorax, 

 a point under the wing, tw r o spots on the scutellum, and the borders 

 of the 1st and 2d segments, yellow. The abdomen, except the 

 petiole, of a brown purple or ferruginous. Feet black, varied 

 with ferruginous. Wings washed with bro"wn-yellowish, nervures 

 brown; wing scales bordered with brown or yellow. 



%. Clypeus very flat, punctured; its inferior margin advanced 

 in the middle, entire ; a smooth lozenge or triangle in the middle 

 of its inferior extremity ; this piece is black, covered with gray 

 hair — its lozenge-shaped part smooth, often yellow. Antennas 

 black, with front of the scape yellow and terminated by a little 

 ferruginous hook. 



Bess. a. diff. — See the affinities of Z. Chicotencatl and Poeyi. 



The Z. niger offers also two metathoracic carina? starting from 

 the angles of the post-scutel; but in this species the post-scutel 

 is not crenulatecl, and there is between these carinas a concave 

 pit, while here the two moieties of the metathorax remain convex 

 and are separated by a deep furrow. The thorax and the head 

 are also smaller, etc. 



Hab. The gulf side of Mexico. Tampico. I have taken but 

 one specimen ( % ). 



By the very remarkable form of its clypeus and its mandibles, 

 4 



