134 BULLETIN 31, UNITED STATES NATIONAL MUSEUM. 



lower part of the face projects more than iu B. notata. The third joint 

 of the antennae is distinctly smaller than that of the females of either 

 of the preceding species. 



VOLUCELLA.* 



Volueella Geoffroy, Hist, ilea Insects de Environs de Paris, vii, 1764. 

 Cenogaster Dumeril, Exposition, etc., 1801, and Diet. d'Hist. Natur. Strasbnrg, 



1817. 

 Temnocera St. Fargeau and Serville, Encycl. Metli., x, 786, 1825; Macquart, 



Dipt. Exot., ii, 2, 26. 

 Ornidia St. Fargeau and Serville, Encycl. Meth., x, 786, 1825. 

 Atemnocera Bigot, Bullet, bi-mens. Soc. Ent. France, No. 12, 1882. 



Medium to large size, robust, sometimes thickly pilose, black, metal- 

 lic blue, brownish-yellow with darker abdominal tasciae, or nearly 

 wholly yellowish species. Head somewhat broader than the thorax, 

 the i^osterior orbits narrow. Antenna? comparatively small, first two 

 joints short, of nearly equal length, third joint elongate, sometimes 

 slender, often narrowed in its middle or toward the end; arista plumose, 

 sonietimes with long and abundant pile, at other times shorter, sparser. 

 Face more or less excavated below the autenn?e, with a prominence be- 

 low the middle, at other times straight or convex in profile, the epistoma 

 considerably produced downwards and somewhat forwards, conical, 

 poi,nted at the tip, with a small notch. Eyes pilose, sometimes bare iu 

 the female, coutii^uous above in the male. Thorax sometimes with 

 yellow lateral stripes, sometimes densely i)ilose. Scutellum large, often 

 translucent, sometimes with hairs or distinct bristles on its border. 

 Abdomen oval, strongly arched, not very much longer than the thorax. 

 Legs simple, moderately strong, all the femora of nearly equal length. 

 Wings large and broad, marginal cell closed, anterior cross-vein usually 

 towards the base of the discal cell and rectangular, sometimes near the 

 middle and oblique. Third longitudinal vein not bent into the first 

 I)osterior cell, fourth vein bent inwards at the end, the third vein beyond 

 the union directed obliquely forward; calyptrce large. 



The face in the female frequently differs in profile somewhat from that 

 of the male, the depression below the antennne being a little greater, 

 and the lower part of the face more receding; the third joint of the 

 antenna;, also, is sometimes more expanded, especially at the base. 



Contrary to the opinion of some excellent dipterologists I have re- 

 jected the genus Temnocera, for the following reasons : In several of 

 the species of our fauna, bristles or bristly hairs exist on the scutellum 

 and i)ost-alar callosities. In some of these, to separate them generically 

 would be absurd, for the conformation and coloration throughout are 

 strikingly similar to those of others without. Moreover, the bristles 

 in some are so fine that they are with difficulty distinguished. Hence 



•Diminutive from rohtctr, swift. 



