STIZUS. 



277 



radial cell: abdomen elongate, massive, the 1st segment never 

 petiolate or narrowed, its base generally truncate or steeply sloped ; 

 no furrow between the 1st and 2nd ventral segments ; pygidium 

 bare, convex, the apex rounded, margined. 



Very little is known of the habits of the species of this genus. 

 In Burma S. rufescens, Smith, was common in the hot weather on 

 the sandy banks of rivers, sitting on the damp sand in company 

 with Megachile, Nomia, Bembex, &c. I never found its nest, but 

 once caught a $ carrying a small Cicada. 



Key to the Species. 



A. Wings fuscous. 



a. Wings not hyaline at base or apex .... S. vespiformis, p. 277. 



b. Wings hyaline at base and at apex. 



a'. Apical three segments of abdomen 



red S. calopteryx, p. 278, 



b'. 2nd and 3i'd and base of 4th segment 



of abdomen only red S. cornutus, p. 278. 



c. Wings hyaline at apex of fore wing only. S. bla/idinus, p. 279. 



B. Wings ilavo-hy aline. 



a. Median segment striate at apex S. melleus, p. 280. 



b. Median segment not striate. 



a'. Eyes with the inner orbits parallel. 



Length 20-2.5 mm <S. rufescens, p. 280. 



b'. Eyes with the inner orbits divergent 



towards the apex. Length 14-20 



mm S. biclipeatus, p. 279. 



C. Wings clear hyaline. 



a. Head yellow, vertex only black. Length 



16 mm S. melano.vanthus, p. 283. 



b. Head black, the clypeus, a line along the 



inner orbit, and the scape of the an- 

 tennae onh' yellow. Length 7-10 mm. 

 a'. Vertex around the ocelli punctured ; 

 mesonotum anteriorly with two 

 parallel longitudinally impressed 



lines S. reversus, p. 281. 



b'. Vertex and mesonotum smooth, 

 a^. The yellow markings on the thorax 



and abdomen large, conspicuous . S. lateralis, p. 281. 

 b^. The yeliow markings on the thorax 

 and abdomen small and not con- 

 spicuous S, prismaticus, p. 282, 



504. Stizus vespiformis. 



Sphex vespiformis, Fabr. Sj)ec. Ins. i, p. 447, 



Stizus vespiformis, Dahlh. Ilym. Eur. i, p. 154 ; Cam. Mem. Manch. 

 L. Ph. !ioc. (4) iii, 1890, p. 246 ; Handl. Sitzunysb. Akad. Wiss. 

 Wien, ci, 1892, p. 147. 



2 . Head, pronotum, and abdomen smooth and shining ; meso- 

 notum, scutellum, postscutellum, and median segment with 



