l6o TRANS. ST. LOUIS ACAD. SCIENCE. 



thorax with the basal area small and elongate, the central area enormously 

 large and divaricated widely behind so as to cut off the lateral areas, which 

 have no cross-carina, from the posterior area. Tegulae white. Abdomen regu- 

 larly oval, opaque, very minutely and densely punctate, subpolished towards 

 the tip and the tips of the joint. Joint I strongly arched, 2$ times as long 

 as wide, thrice as wide behind as before, its sides straight except at the ex- 

 treme tip, where they are first incurved and then excurved in a blunt tuber- 

 cle, behind and outside which in the following joint is a similar tubercle; 

 the two usual carina? faintly traceable to the tip, and enclosing a shallow 

 excavation. Joints 2 and 8 as broad as long, and 8 curved upwards at tip 

 as in Xylonomus $ ; 3 and 7 shorter by \ than broad ; the rest short. The 

 extreme terminal edge of 3-7 whitish, which in 5-7 is due only to the con- 

 necting membrane being white. Ovipositor f as long as the body, inserted 

 \ of the way from the tip of the abdomen to its base ; sheaths black, ta- 

 pered, pubescent, basally half wider than the last tarsal joint of the hind 

 leg. Venter longitudinally carinate, scarcely excavated, black, the sutures 

 whitish. Legs rufous ; front legs with the tibiae strongly inflated ; middle 

 legs with the basal \ of the tibiae, and the basal \ of the 1st tarsal joint, 

 white; tip of tarsus brown. Hind legs with the terminal \ of the femora 

 and the tibia? and tarsi black, save that the knees, the basal \ of the tibiae, 

 the spurs, and the basal £ of the 1st tarsal joint, are all white. Wings hya- 

 line; veins black; stigma black, its extreme base white. Radial area mod- 

 erate ; its posterior angle about 120 . The 1st recurrent vein slightly curved 

 inside the middle; the 2d slightly convex outside. Length $ .25 inch. 

 Front wing ? .20 inch. Ovipos. .10 inch. 



One 2 ; 6" unknown to me. The front tibiae are similarly in- 

 flated in E. reluctator (Europe), in two Canadian species [fiiger, 

 Cress., and abdominalis, Cress.] and in Cryptus? ornatipennis, Cress. 

 (Cuba), which, like annulicornis, has the last two abdominal joints 

 very large, and the last upcurved as in Xylonomus 9. It is only 

 this last joint that is here rufous, and not the last two as is stated 

 by Cresson. 



Genus LABENA, Cresson (= Mesochorus, Brulle non Gravenhorst). 



Head subcubical ; the space between the eyes widest at the 

 insertion of the antennas, thence narrowed rapidly towards the 

 vertex, more slowly towards the mouth, so that the eyes are 

 slightly but distinctly emarginate. Clypeus moderate, transverse- 

 ly suboval, almost entirely concealing the labrum. Mandibles 

 bidentate. Antenna? 6* about as long as the body, ? about i as 

 long as the body ; o" 2 neither tapered nor clavate ; joint 1 very 

 obliquely truncate on the outside, and enclosing nearly the whole 

 of joint 2 ; joints of the flagellum rather short. Thorax with the 



