1. PHILONICUS 637 



A large yellowish ashy grey fly, resembling Machimus 

 rusticus and Eutolmus rufibarbis but lighter colored than any 

 British Asilid except the very distinct Di/smachus trigonus. 



$ . Face broad, densely covered witli whitish or pale yellowish grey tomentum ; 

 facial knob small ; face-beard long and drooping, whitish yellow or white but 

 with the uppermost (3-20) hairs black less drooping and more bristly ; upper 

 half of the face and sides of the knob bare ; chin-beard long, dense, and 

 white : jowl-beards rather shorter, dense, shaggy, hanging straight down, and 

 extending more sparsely nearly half-way up the back of the head ; pubescence 

 above the middle of the back of the head pale yellowish, shorter and sparser 

 (though still abundant) ; festoon represented by about twelve stout yellow 

 bristles which are not quite close to the eyes but which extend all across 

 behind the vertex so that there is only a small gap at just the middle of the 

 postvertical depression, and even the uppermost bristles hardly bent forwards 

 at their tips ; vertex bare on the depressed channel between the eyes and on 

 the forks of this channel which extend down the sides of the ocellar space, 

 but the sides of the frons from the upper ocelli to the antenna? bearing some 

 rather short black bristly hairs at first on the orbits only but lower down more 

 out on the frons itself ; frons greyish white, ocellar space bearing some black 

 bristly hairs, but many of the thinner hairs about and between the ocelli 

 whitish ; sometimes a few thin black hairs occur in front of the postvertical 

 bristles, and sometimes a few thin whitish hairs are intermingled amongst those 

 on the upper part of the sides of the frons ; back of the head lighter grey, with 

 an indefinite dark streak or blotch extending downwards from the postvertical 

 bristles along the space on which the festoon bristles occur ; actual back of 

 the head bearing fine whitish hairs ; collar yellowish grey, bearing on the 

 upper part six or more stoutish yellow bristles (though sometimes one or two 

 of the uppermost of these may be black) besides numerous fine pale hairs. 

 Proboscis shining black, rather long, and bearing short pale pubescence about 

 its tip and long rather sparse pale pubescence beneath on its basal half ; palpi 

 short and thin, bearing porrect pale hairs. Antennae dull black ; two basal 

 joints tinged with grey_ and bearing numerous black bristles with sometimes a 

 few pale hairs intermixed on the underside of the basal joint ; third joint 

 hardly so long as the two basal joints together, minutely pubescent dorsally 

 just before its middle ; style quite as long as the third joint, linear with a 

 very short thin tip. 



Thorax yellowish ashy grey with the usual dark stripes well defined ; 

 middle stripe blackish, or (if brownish black) with its borders blackish (best 

 seen when viewed from in front or behind), broadened anteriorly but gradually 

 narrowed posteriorly quite to the hindmargin, and split by a lighter yellowish 

 grey line (which in its turn is sometimes forked quite in front) not quite to 

 the hindmargin ; side-stripes large and broad, greyish brown but well con- 

 trasted against the yellowish grey ground colour, beginning about half-way 

 between the front and the suture, rather narrowly interrupted at the suture, 

 and continued afterwards as smaller parts which are rounded at both ends, 

 and followed by the usual more blackish bi'own awl-shaped (sometimes fainter 

 and curved) spots which do not nearly reach the hindmai'gin ; humeral stripes 

 represented by dark isolated triangular spots. Pubescence (as distinguished 

 from strong bristles) on the dorsum of the thorax composed of small sloping 

 black bristles over nearly all the disc, though sparse above the wing-base and 

 on and about the back part of the postalar calli and absent on the blackish 

 brown aAvl-shaped spots ; tliese small bristles are very short on the front half 

 but thence grow gradually longer towards the hindmargin, though they can 

 never be confused with the true bristles unless with the last one or two of 

 the dorso-central rows ; besides these bristles fine short pale brownish yellow 

 or whitish yellow inconspicuous pubescence occurs on the humeri, above the 

 wing-base, on and about the front i)art of the postalar calli, and in fact some- 

 times scattered anywhere about the disc. Macrochjetse or strong bristles 

 varying extremely in colour between black and white ; praesutural normally 

 two long and strong, sometimes both black, but sometimes the hind one or 



