90 SYRPHID.I. 



of that species are truly known. If so, it differs from ribesii by 

 the hind femora being principally black. In this respect it 

 resembles vitrijjennis, Meig., if this latter is really distinct. 

 Yerrall states of vitriftennis, in comparing that species with his 

 wonderfully correct description of S. ribesii, that its best specific 

 distinction from the latter is " the scarcity of the tiny black 

 bristles about the tip of the hind femora in both sexes." In ribesii 

 these bristles are wholly yellow on all the femora except the 

 middle pair (where they are black) ; in vitripennis they are all 

 black and scarce. In the present form they are black and numerous. 

 The hind tibiae are all black except about the basal third, whereas 

 in ribesii there is at most an obscure dark patch on the front side, 

 and in vitrijyennis the tibia3 are wholly yellow. The present form 

 is as distinct from both ribesii and vitripennis as these two are 

 from one another, but it is still open to question whether the 

 three forms are not merely three well-marked varieties of one 

 species. There are so-called " species" in jSTorth America so near 

 ribesii that further confirmation of their distinctness would be very 

 satisfactory. 



72. Syrphus aequalis, Wall-. 



Xi/lota cequalis. Walker, Ins. Saund., Dipt, i, p. 220 (1852). 

 Si/rphus distinctns, Brunetti, Rec. lud. Miis. xi, p. 211, pi. xiii, fig. 7, 

 abdomen (1915). 



(S . Head : frons, face and under side of head covered with pale 

 orange-yellow tomentum, this being more dusky towards the 

 frons ; a broad median blackish stripe ; frons with black hairs ; 

 vertex blackish with black hairs. Antenna? and arista wholly 

 black. Back of head dark grey with short yellow hairs, some 

 black ones behind the vertex. Thorax: blackish on dorsum, 

 yellowish-grey at sides, mainly covered with brownish-yellow 

 pubescence. Scutellum orange-yellow, with black hairs in the 

 middle and yellowish-white ones on anterior and posterior margins 

 and below the latter. Abdomen : blackish, 1st segment yellowish, 

 hind margins of 2nd, 3rd and 4th segments pinkish-grey, with 

 a rather narrow cross-band of the same colour across the middle 

 of each, the first band narrowly interrupted ; that of the 4th 

 segment lying just below the middle. Dorsum of abdomen with 

 i-ather thickly placed black hairs except on the 2nd segment, on 

 the pale band on the 3rd and at the sides of the whole abdomen, 

 where the pubescence is whitish-yellow. Venter blackish, 

 yellowish at base and along the hind borders of the segments, 

 covered with yellow or black pubescence according to the colour 

 of the surface. Ler/s : anterior pairs principally orange-yellow ; 

 anterior femora blaclc on about the basal half ; hind legs principally 

 black, knees broadly brownish-yellow as are tlie last four tarsal 

 ioints. Anterior femora with some moderately long yellowish or 

 brownish-yellow hairs on under side, with black hairs intermixed 

 towards tips of fore pair and generally on under side of middle 



