WALSH DESCRIPTIONS OF N. AM. HYMENOPTERA. IO5 



Genus EXENTERON, Hartig. 

 Section i . — Areolet rhomboido-triangular. 



ExeilterOIl OmatUS, n. sp.—cf.— Black. Head large and \ wider than 

 the thorax, subpolished, with very minute, sparse punctures ; the face sub- 

 opaque and indistinctly rugoso-punctate. Face, a short, narrow orbit just 

 passing the antenna;, cheeks below the eye, clypeus, and mandibles except 

 their teeth, all yellow. 'Palpi whitish. Antenna; as long as the body, brown- 

 black on their basal \ save that the scapus is yellow beneath, the other \ 

 gradually rufous; 1st joint of flagellum 34 times as long as wide. Thorax 

 polished, with very minute, sparse punctures. Metathorax subopaque and 

 finely rugose, with its carinate areas all complete ; the central area \ longer 

 than wide, rounded in front, and with its sides straight but slightly conver- 

 gent behind. Tegulae, a line under the front wing, a pointed line clavate 

 behind adjoining the tegula and underlying the humeral suture h way to 

 its tip, scutel and a transverse line behind it, and also the prosternum, all 

 yellow. Abdomen short, depressed, broadly obovate, subpolished, with very 

 fine, sparse punctures which are subobsolete towards its tip and the tips 

 of the joints. Joint 1 squarely truncate in front, with the apex of its anterior 

 angles prolonged a little, £ longer than wide, £ wider behind than before, 

 its sides parallel f of the way to the tip, thence gradually diverging; the 

 2 usual carina; distinct | of the way to the tip. Joint 1 black, with an ob- 

 trigonate, rufous, dorsal spot on its terminal J; the rest of the abdomen 

 pale rufous. Venter pale rufous. Legs pale rufous ; the 4 front legs with 

 their coxae and trochanters yellowish-white, but the middle coxa; with 

 their anterior face rufous. Wings long, hyaline; veins black; stigma 

 black, its basal \ whitish. Areolet sessile, rhomboido-triangular, and ob- 

 liquely elongate, the 2d recurrent vein entering it full § of the way to its 

 tip. Bulla; 4, A, B, C, and E ; A and B on the exterior cross-vein of the 

 areolet and separated by a considerable space, C midway between the sa- 

 lient angle and the areolet, and E rather nearer to the angle of its vein 

 than to the areolet. Length c?. 17 inch. Front wing o* .17 inch. 



One a ; ? unknown to me. 



Section 2. — Areolet triangular. 



Exeilteron flaviCOXUS (Cteniscus jlavicoxa;, Cress., 5 only described). 

 —^.—Differs from the preceding 6* only as follows:— i. The orbit is pro- 

 longed to the vertex, much contracted in width opposite the antennae, 

 thence widening till at the commencement of the vertex it is expanded 

 into a short, blunt, robust bifurcation. 2. The yellow cheeks are widely 

 prolonged behind the eye, so as to be only separated from the frontal or- 

 bits by a space equal to \ the shorter diameter of the eye. 3. The antennae 

 are only | as long as the body. 4. The 3 cross-carinae of the metathorax 

 are subobsolete ; the yellow line under the humeral suture is much wider 

 and extends twice as far forwards, and there is a square yellow spot on 

 the disk of the mesonotum. 5. The abdomen is elongate-subolong, joints 

 2-5 being of uniform width. Joint 1 is \ narrower at tip than the base of 



