496. 

 DIODONTUS GRACILIS. 



Order Hymenoptera. Fam. Crabronidae. 



Tyjpe of the Genus, Psen pallipes Pans. 

 DioDONTUs Curt. — Stigmus Lat. — Pemphredon Fab., Vand. L. — 

 Psen Panz. — Crabro Fah. 



Antemicc inserted below the naiddle of the face, a little longer 

 than the head, velvety, filiform, and IS-jointed in the male ; 

 12-jointed in the female (1), basal joint the longest and stoutest, 

 subpyriform and truncated obliquely, 2nd obovate, 3rd rather 

 more slender and oblong, the remainder a little stouter, of equal 

 length and oblong, terminal joint longer and ovate at the apex. 

 Labrum semiorbicular, notched in front, forming two obtuse 

 points, slightly produced, the margin producing a few bristles 



Mandibles alike, long, narrow, obtuse, pilose, truncated obliquely 

 and notched, forming two rounded and concave teeth, the lower 

 one with a series of bristles on the inside (3). 

 Maxilla terminated by an oblique subovate lobe, very pilose at 

 the apex, with a porrected one on the inside, producing a few 

 bristles. Palpi long, hairy and 6-jointed, basal joint the shortest 

 and slenderest, 2nd and 3rd very broad, the remainder slender 

 and attenuated to the apex, 4th the longest, 5th and 6th not 

 longer than the 2nd and 3rd (4). 



Mentum oblong, a little dUated before. Labium very short and 

 fleshy. Palpi rather long, pointed and pilose, basal joint long, 

 naked and clavate, 3 following much shorter, nearly of equal 

 length, the 3rd a little the shortest, 4th a little narrower and 

 ovate at the apex (5). 

 HqvA broad, face orbicular, concave: eyes lateral and ovate : ocelli 3 

 in triangle on the crown of the head. Thorax obovate. Abdomen 

 elongate conic or ovate ; petiole very short. Wings with 3 submar- 

 ginal cells, the \st long, the 2nd small, obloiig or rhomboidal and 

 3 discoidal cells. Legs, anterior the shortest : thighs slightly in- 

 crassated : tibiae short, slender at the base, anterior with a broad 

 spine at the apex, the others with 2 slender ones, the posterior gene- 

 rally spiny outside in the females : tarsi long, especially the poste- 

 rior, 5-jointed, basal joint very long, the others short and decreasing 

 in size to the apex, the terminal joint being clavate : claws small (8, a 

 fore leg). 



Gracilis Curt. Guide, Gen. 685^. 1. 



Male black, slender ; head and thorax very thickly and minutely 

 l)unctured, the former with the lower part of the face clothed 

 with silvery hairs ; palpi and a stripe outside the mandibles 

 ochreous-white ; metathorax coarsely reticulated, shining : ab- 

 domen very glossy, minutely but not thickly punctured, seg- 

 ments coarctate especially at the base, the apex ferruginous 

 with a recurved spine : wings quite transparent, nervures and 

 stigma piceous, 2nd submarginal cell oblong, very little nar- 

 rowed above : tips of thighs, base and tips of tibiae and tarsi 

 ochreous, excepting the hinder pair and the apex of the others. 

 In the Cabinets of Mr. Shuckard and the Author. 



