WALSH DESCRIPTIONS OF N. AM. HYMENOPTERA. 153 



times as long as wide, and elongate-rhomboidal, the tip of the 2d joint 

 abutting on the lateral angles of the rhomb, and the extreme base and tip 

 of the rhomb being truncate. Joint 2 only £ wider than long. Ventral 

 joint 6 small. 5. There is no spot under the tip of the hind femora. 

 Length rj? .37 inch. Front wing q" .35 inch. 



One 6* ; three ? . Ac. stigmaterus, Say, is a Xylonomus. Ac. de- 

 corus, Say, is an Arotes. The only remaining N. A. species that 

 has been referred to this genus is Ac. melleus 2 , Say, which pro- 

 bably belongs here, but differs from rupinsulensis 2 in the antennae 

 being white with their basal i black above (not rufous immacu- 

 late), in the occiput having a dusky spot, and in the sutures round 

 the scutel and on the abdominal dorsum being blackish. 



[Genus PHYTODIETUS, Grav.] 



Head with^the face triangularly hunched under the antenna?. 

 Clypeus small, transversely oval, hunched, and prominent. Man- 

 dibles bidentate. Antenna? slender, about as long as the body, 

 the 1st joint laterally and obliquely truncate ; joints of the fiagel- 

 lum rather long. Thorax with the parapsidal grooves subobso- 

 lete ; the metathorax nearly smooth. Abdomen minutely punctate 

 and polished, with no striae or tubercles, elongate-oval, subsessile 

 6*, subpetiolated 2- , the ist joint long and tapered gradually to its 

 base ; joint 2 much shorter ; the remaining joints slowly shorter 

 and shorter. Venter longitudinally carinate throughout, 6* slightly 

 depressed, 2 slightly depressed towards the base, strongly com- 

 pressed and protuberant towards the tip. Terminal joints of the 

 abdomen not $ 2 retracted, and the 6th ventral ? not materially 

 prolonged. Ovipositor moderately long. Legs long and slender, 

 especially the hind legs ; tibiae all with an irregular double exter- 

 nal row of minute thorns directed obliquely backwards, more 

 conspicuous on the hind tibiae ; spurs normal ; claws pectinate ; 

 pulvillus shorter than the claws. Wings long ; radial area and 

 stigma rather long ; areolet small, sometimes peduncled, triangu- 

 lar, the 2d recurrent vein, which is regularly convex externally, 

 entering it at its extreme tip ; ist recurrent vein curved suddenly 

 and strongly near its base. Bullae four, B, C, D, and E ; B small 

 and indistinct, normally located ; C and D separated by a wide 

 space, and E normal. 



Allied to Banchus by its pectinate claws, but differs by its abdo- 

 men not being sessile, by its ovipositor not being rather long, and 



