56 HYMENOPTERA OP AMERICA. [PART I. 



Gen. LABIS Sadss. 

 m Saoss. Reise .1. Oesterr. Pregat. Novara. Hym., p. 3. 



Mandibles short, obliquely truncate, with 3-4 terminal teeth. 

 Maxilla elongate; their palpi elongate, G-jointed. Labium 

 elongate, quadrifid, its palpi 4-jointed. Head rounded, swelled 

 at ihr occipul ; clypeus rounded or truncate. 



TJwrax elongate; its anterior angles sharp. 



Abdomen very slender; its petiole elongate, linear. Wings 

 somewhat as in Eumenes and Zethus. 



A.s the forms of the insects of this type are becoming various, 

 one could well think that the genus Labus might be fused into 

 G. Elimus, which only differs from tins by another form of thorax 

 and petiole. Such differences occur under the species of the 

 genus Zethus. 



A. I' iform at base, a little toidened posteriorly; its 

 extremity margined by a transverse rounded cordon pre- 

 ceded by a transverse channel (as in Eumenes of Division 

 Omicron). Second segment sessile, elongate. Metathorax 

 attenuated. Head inflated. Second cubital cell much pro- 

 longed at the basilar extremity ; the second recurrent vein 



rted after the middle of its posterior border. {Asiatic 

 type.) L. Spiniger Sauss., L. Humbertianus Sauss. 



B. Petiole linear, slender, prismatic; 2d segment subpedicu- 



Thorax elongate; metathorax short; prothorax 

 crested anU riorly. Second cubital cell equally dilated at 

 both extremities; second recurrent vein inserted in the 

 middle of its posterior tinnier. (American type.) 1 



1 The genus Elimus would make a third type: — 



C. Petiole linear, rather thick (very elongate, somewhat pyriform),biden- 



tate; its extremity marked with an impressed point; head moderate; 

 thorax oval, not acute augled anteriorly; metathorax rounded; the 

 2d segment elongate, rather attenuate posteriorly; 2.1 cubital cell in 

 a regular truncate triangle; second recurrent nerve inserted in the 

 middle, or a little before tin; middle, of its posterior border. 



