24 syephidjB. 



bump often absent; the wliole face sometimes conically and 

 conspie'uously projected forwards or diagonally downwards (Ascia, 

 Rhin</ia, Volucella), sometimes eTiormously so (Lr/castris). In 

 some genera, especially in tliose in whicli tlie frons is distinctly 

 produced, with the antennae set at the extreme tip, the face 

 descends almost perpendicularly from below the antennve ( Chryso- 

 toxum, Ceria) ; in others it forms a uniform convexity (^Nicrodon). 

 Sides of face sometimes with distinct eye-margins (Ckilosia), 

 which usually bear a different kind of pubescence to that of the 

 rest of the face. Frons and face varying from entirely bare to 

 densely pubescent. Antennae generally situated distinctly above 

 middle of head in profile ; normally comparatively short, drooping ; 

 1st and 2nd joints very short, 2nd more or less cup-shaped, 

 generally widest at tip, 3rd rounded, oblong, ovate or elongate : 

 in some genera the whole antenna is conspicuously elongate 

 (Chri/sotoxum, Microdon, Mixo(jaster). Arista dorsal, nearly basal, 

 varying from entirely bare to densely and long \A\imose (Volucella^. 

 Proboscis soft, generally short or moderately long, seldom as long 

 as height of head ; rare exceptions occur in which it is extremely 

 long and attenuated, as long as the whole body (Lycastris) ; labella 

 moderately large ; palpi one-jointed, slender, rarely conspicuous. 

 Three ocelli. 



Thorax quadrate, oblong, oval or sometimes transverse, mode- 

 rately arched, generally with soft pubescence; occasionally some 

 bristly hairs about the humeri, side margins, base of wings or 

 bind corners of dorsum. Scutellum moderately large, generally 

 semicircular, generally concolorous with thorax and similarly 

 clothed ; not infrequently jfellowish and more or less translucent 

 even when the thorax is dark coloured; unspined, with very rare 

 exceptions (Microdon being the only Oriental one). 



Abdomen of at least four distinct segments *, usually five or six, 

 a seventh sometimes present in Sj^hcBrophoria ; very variable in 

 shape, curvatuie and thickness ; sometimes longer and narrower 

 than thorax (BaccJia, SpJuerojjhoria) ; ovate {Syrjilins etc.); flat 

 and broad (Didea), linear (Platyehirus, Xylota); cylindrical 

 (Syritia) • clavate {Ascia, Baccha, Doros, Cerin) ; short and rounded 

 and densely ]:)uhesce\\t (Crio7-r7iina, AretojjMla) ; in the majority 

 of genera only moderately pubescent. Genitalia usually not 

 prominent, often wholly concealed, the d" organs normally twisted 

 to the right ; in 5 simple. 



Leys generally simple and not strong, especially in 2 '- ''^ the 

 c? in some genera bearing tooth-lihe or spiny processes, or actual 

 spines or bristles, on under side of hind femora ; tihias often curved 

 or twisted. In one genus {Platyehirus) the legs in the c? afford 

 strong stT'uctural characters in most of the species. 



Wings with a characteristic and rather constant venation. 

 Auxiliary vein ending at about middle of wing; 1st and 2nd veins 

 long, slightly sinuous; marginal cell open or closed near margin ; 

 submarginal cell always widely open. 3rd vein always simple, 



* One European gemis, Triglyphus, has only tliree obvious segments. 



