24 HYMEXOPTERA OF AMERICA. [PART I. 



angles not spiny; post-scutel feebly bilobate ; metathorax con- 

 vex, slightly divided by a simple furrow, strongly wrinkled — its 

 lateral edges sharply carinate. Petiole of moderate length, its 

 enlargement not being oval but in form of a tube slightly flat- 

 tened, a little compressed behind, punctured; the remainder of 

 the abdomen pear-shaped, the 2d segment bell-shaped, a little 

 pediculate, slightly funnel-shaped, offering a second distinct 

 border, not turned up at edge. 



The whole insect of a shining black, everywhere garnished with 

 a pile of tawny hair; a transverse spot on the forehead, sinus of 

 the eyes, a spot behind each eye, a large border on the prothorax, 

 a spot under the wing, wing scales, two spots on the scutellum, 

 a band on the post-scutel, and two large spots on the posterior 

 face of the metathorax, yellow. Segments of the abdomen all 

 narrowly bordered with yellow; legs yellow, thighs varied with 

 black. Wings transparent, nervures ferruginous. 



%. Clypeus yellow, convex, terminated by a truncate projec- 

 tion; mandibles yellow; antennas entirely orange or ferruginous, 

 only a little dull above ; the scape marked with a yellow line ; 

 the 3 last articles forming a rolled spiral. 



Bess. a. diff. — This species is distinguished by the color of 

 its antenna?, and especially by the form of its petiole. This form 

 resembles a little that of Z. miniatus, but that has the angles of 

 the prothorax dentiform and the petiole more cylindric and 

 coarsely cribrose. 



The Z. Heydeni is much less coarsely cribrose than the Z. 

 Aztecus, Westwoodi, or chrysopterus, which it slightly resembles ; 

 and the exceptional form of the clypeus, %, also distinguishes it 

 clearly : for with these species the clypeus is large, quadrate, the 

 same as with the Z. Jurinei, which is less punctured and has the 

 wings obscure. The enlargement of the petiole is also very much 

 more globular than among all these species. 



Finally, this Zethus might be confounded with some one of 

 those species described by Smith, and which we cite at the end 

 of the genus; but the author having omitted to indicate divisions 

 into which these species enter, or the characters which permit one 

 to classify them with precision, it is not possible to recognize 

 them with certainty. The Z. carinatus presents much the same 

 appearance, but it is very much smaller. 



Hah. Brazil. (Museum of Senkenberg.) 





