Syrphidae. 25 



haired, and the hind femora may be quite short-haired ; in some cases 

 tlie tibiæ may be a little fringed, especially the hind tibiæ; the 

 hind femora are in some genera more or less setulose below; other- 

 wise the legs have no bristles, only two exceptions occur; Volucella 

 inanis has bristles on the anterior tibiæ, and in the genus Ferdinandea 

 there are a few bristles on middle femora and on the tibiæ. The 

 front and hind tibiæ and tarsi have a curious, short, adpressed, gener- 

 ally yellow or reddish pubescence, on the front legs present on the 

 apical half of tibiæ on the anterior and ventral side, and below the 

 basal part of the tarsi, on the hind legs on posterior and ventral side 

 of tibiæ and base of tarsi. In all (or nearly all) genera the trochanters 

 have a special, solitary long hair or bristle above, sometimes most 

 distinct on the anterior legs, and sometimes it does not seem to be 

 present; likewise there is, I think always, a cm-ious, more or less 

 circular, scabrous patch on the anterior side of the femora at the 

 base; this patch is formed of short, more or less squamose hairs; in 

 some groups it is specially distinct (as in the Eristalinae) and then it 

 is "formed of quite short, distinctly squamose hairs, while in other 

 cases it is only slightly pronounced, the hairs forming it being less 

 squamose, but differing from the other clothing by being quite short. ^ 

 While the legs are in most cases equal in both sexes or only a little 

 different, they show in a few genera {Platychirus, Ptjrophaena) secon- 

 dary sexual characters generally to a great degree; in the male then 

 the front tibiæ and tarsi, or only the tarsi, are dilated in various 

 ways and generally specially coloured, and also the middle tibiæ are 

 generally specially shaped; at the same time the front femora and 

 generally also tibiæ, and also often middle femora and tibiæ are 

 specially haired. There are two well developed claws and pulvilli, 

 and a bristle- or spine-shaped, generally short empodium with small 

 hairs. Wings of usual shape, only rarely a little elongated or on the 

 contrary short. Costa continued to the end of the cubital vein; the 



These two characters are rather curious and interesting; the soUtary hair on 

 the trochanters is inentioned by Verrall as a character for Helophilus lineatus, 

 but the hair is, I think always, present; in the descriptions of the genera I 

 have not ahvays mentioned it; it may be shorter or longer and sometimes 

 represented by a pair of hairs; in some cases it is not easily detected when 

 the hairs of the common clothing are long and dense, so ihat it may be more 

 or less hidden; sometimes it is rather short, and it is often most easily seen 

 on the anterior trochanters. The patch of squamose hairs has been mentioned 

 by Verrall especially for the Eristalinae, and it is distinctly seen in some of 

 his figures ; in this subfamily it is also specially distinct, but it is likewise no 

 doubt always present, but very varying in development, the hairs being more 

 or less squamose but always different from the common clothing around it. 



