Therevidae. 135 



the second short, globular, the third generally the longest, at the 

 apex with a small, two-jointed style the first joint of which is short, 

 the second terminating in a bristly apex; sometimes the antennæ 

 have the first joint thickened; the first joint has long hairs on the 

 basal part and stronger bristles on the apical part, the second joint 

 has shorter bristles. There is no real oral cone, only small connecting 

 membranes; epistoma somevvhat short, retreating; clypeus represented 

 by two chitinous hsts, connected above, or it is more or less horseshoe- 

 shaped ; it reaches almost horizontally from the epistoma to the labrum 

 and is separated from the cheeks and jowls by a membrane. Pro- 

 boscis short, scarcely half as long as the head is high. Labrum 

 elongate triangular, truncate and triangularly emarginate at the apex; 

 the maxillæ have a thin, pointed lacinia and one-jointed palpi which 

 are long, longer than the lacinia and with long hairs; the stipites of 

 the maxillæ are small, lying laterally on the posterior side of the 

 membrane connecting the labium with the oral aperture. Hypo- 

 pharynx slightly narrower than labrum; with parallel sides, truncate 

 at the apex. Labium with a short basal part and large and broad 

 labella which are twice as long as the basal part. Labrum, maxillæ 

 and hypopharynx of equal length and somewhat longer than the basal 

 part of labium, about half as long as the whole labium. Thorax 

 rectangular, somewhat longer than broad, shghtly arched above. 

 There are four strong bristles in front of the wing-root which may, 

 on account of their position on the præalar cailus (which is here 

 large, the præsutural depression in which the cailus lies being extended, 

 but faint) be termed notopleural bristles, further generally two supra- 

 alar bristles, one postalar bristle on the postalar cailus, and one or 

 two dorsocentral bristles in front of the scutellum (the number is not 

 quite constant and may be one or two in the same species, yet some 

 regularity prevails and I shall therefore mention the number in the 

 specific descriptions); finally there are four scutellar marginal bristles. 

 The metapleura have a tuft of long hairs. Abdomen almost cylindrical, 

 at the base about as broad as thorax, but it is pointed towards the 

 apex and thus conical ; it consists of seven not transformed segments. ^ 



1 In earlier descriptions, especially those by Loew, the hind mai'gins of the 

 segments are often mentioned and their colour and breadth are used as 

 characters. These hind margins are seen as more or less narrow posterior 

 horders to the segments of a colour more or less pale than the segment itself ; 

 this border belongs in reality to the connecting membrane and forms the 

 somewhat chitinised front part of this membrane (as in many other Diptera); 

 it is capable of being folded in under the edge of the segment, and when the 

 abdomen is strongly contracted this is always the case, and then the horders 

 are not seen, but generally they are more or less visible. The horders are 



