53 HYMEXOPTERA OF AMERICA. [PART I. 



yellow. The anterior margin of prothorax, two marginal spots 

 on each wing scale, post-tegulae, two spots on post-scutel, two 

 longitudinal fasciae on the metathorax, the end of petiole and the 

 margin of the abdominal segment, yellow ; the lamellar margin 

 of these also yellow or ferruginous, as well as the margin of the 

 anus. A spot at the end of the femora and a line on the tibiae 

 of the first two pair, yellow. Wings snbhyaline with brown veins ; 

 the 2d cubital cell subtriangular ; its radial tip very little trun- 

 cate; the second recurrent nerve inserted in the middle of the 

 posterior margin. 



JSess. a. diff. — This remarkable type has a certain resemblance 

 to the Eumenes of Division Zeta, because of its elongate linear 

 flattened petiole; but this is not so much, flattened, nor parted by 

 a furrow, but prismatic, and the head with its short mandibles is 

 quite that of a Zethus. 



It has a very near relationship to the Asiatic Labus but differs 

 essentially by its prismatic petiole, a form which I have not yet 

 met with in the Wasp. 



Hab. Chili. (This insect was given to me by the celebrated 

 oculist and remarkable entomologist, Dr. Sichel, to whom it is 

 dedicated.) 



Gen. DISCCELllTS Late. 



Lip moderate. Labial palpi composed of four articles. Max- 

 illary palpi composed of six articles. Mandibles short, obliquely 

 truncate. Head often enlarged and a little e margin ate behiud. 

 Thorax lengthened, often angulate before. Abdomen pediculate ; 

 the first segment transformed into a campanular or linear petiole. 



This genus differs from Zethus by its labial palpi composed of 

 four articles, and from Eumenes by the mandibles which are not 

 prolonged in the form of a beak. 



This genus connects itself to Zethus by its mandibles, and to 

 Eumenes and to Odynerus by its complete palpi; the forms of 

 its representatives are also intermediate, in some degree, to Zethus 

 and to Eumenes, and somewhat to Nortonia and Zethus by the 

 snbpedicnlate abdomen. The form of the thorax, often bordered 

 and angulated before, especially assimilates it to that which one 

 sees in the Zethus. 



