1. PHTHIRIA 



487 



31 (30) Underside of the head densely pilose, and hence the root of the 



antennae, epistoma, month, etc., completely hidden. 



Anastcechus. 



32 (29) Upper basal cell longer than the second one (fig. 287). 



Not iiuicli longer in Ploas, of wliicli a few species occur with only 

 two submargmal cells. 



2. BOMBYLIUS. 



Fig. 2S7 .—Bombylius discolor J. x G. 



33 (34) First posterior cell closed (fig. 287). 



34 (33) First posterior cell open (fig. 288). 



35 (36) Basal antennal joint elongate and slender and bearing only 



moderate pubescence (fig. 289). 

 Hind femora spinose beneath. 



DiSCHISTUS. 



Fig. 2SS. —Dischistus minimus, x 12. 



Fig. 289. — Dischistus minimtis. x 32. 



36 (35) Basal antennal joint swollen and bearing abundant long bristly 

 hairs (fig. 279). 



Hind femora not spinose beneath. 



i\^.5. — Most species of Ploas have three submarginal cells (fig. 278). 



Ploas. 



1. PHTHIRIA. 



Phthiria Meigen, lllig. Mag., ii., 268 (1803). 



Small, rather slightly pubescent flies of a light grey or 

 yellowish grey appearance. 



Head of the male nearly semicircular but that of the female almost circular, not 

 broader than high when seen from in front, but about as wide as the thorax ; face 

 broad, but very short down the middle because the large and rather wide mouth- 

 opening extends up between the wide side-cheeks ; frons of the female broad, 

 depressed on the middle part ; ocelli three. Proboscis long and thin, almost like 

 a bristle, directed forwards in a slight arch, and with very small sucker-flaps ; palpi 

 rather short and very thin. Eyes of the male approximated or touching, but of the 

 female widely separated by the broad frons. Antennae (fig. 280) porrect, shorter 

 than the head, and approximated at the base ; two basal joints almost equally short ; 



