1. PHTHIRIA 489 



cheeks are separated from the jowls by a depression, but the jowls merge into 

 the back of the head, and all this part is light grey and fairly puffed out 

 and clothed with rather long yellowish white pubescence up to the vertex, 

 but on the upper third of the back of the head is a postocular fringe of 

 longer thin black hairs ; vertex greyish black, rather large, and considerably 

 elevatecl, clothed with rather long greyish yellow hairs which slope forward. 

 Proboscis dull black, more than twice as long as the head ; palpi small, dull 

 black. Eyes long, being nearly as long as high when seen in profile, some- 

 what four-sided but the front side little more than half as long as the hind 

 side, and this partly caused by a large shallow depression of_ the eyes 

 between the vertex and the frons ; the eyes touch for about one-third of the 

 distance between the occiput and the antennte, but the frontal triangle is 

 longer than the vertical one. Antennae (fig. 280) dull black ; first and second 

 joints short and cup-shaped, about equally long butthe second rather the 

 stouter, and both bearing very short black bristles ; third joint lancet-shaped, 

 nearly three times as long as its broadest part (or the two. basal joints 

 together), and bearing a few very short inconspicuous dorsal hairs ; style so 

 short and thick as to be inconspicuous. 



Thorax and pleurje light grey, but the disc of the thorax usually showing 

 three indistinct broad blackish or brownish stripes which do not extend to 

 the front part ; humeri concolorous ; pubescence on all the upper side 

 composed of rather long greyish yellow hairs, which are all equal and nearly 

 erect but not very dense ; pleurae lighter grey, with similar but whiter 

 pubescence on the mesopleurae, and a slight fringe on the hypopleurtii. 

 •Scutellum more brownish even to the very tip, and bearing similar but rather 

 longer pubescence. 



Abclomen dull brownish black, with pubescence similar to that on the 

 thorax but rather sparser and longer and more radiating and on the basal 

 segment denser, and with traces of sparse pale greyish yellow scaly 

 pubescence all about the disc. Belly light greyish, with rather long sparse 

 greyish pubescence. Genitalia rather knobbed, with two large bulging greyish 

 brown side plates and a long under part which is prolonged into a shining 

 black point. 



Legs dull dark greyish brown ; front coxae long ; all the cox^e and the 

 anterior femora postero-ventrally with long greyish white pubescence ; hind 

 femora with sparse long pale pubescence ; a short scaly adherent whitish 

 grey pubescence exists on all parts of the legs and especially on the_ hind 

 femora, but there are no bristles on the hind femora, and the only spicules 

 are a row of tiny dorsal ones on the hind tibiae ; pulvilli whitish yellow, 

 fairly distinct for so tiny a tip to a tarsus. 



Wings (fig. 281) hyaline, but (when viewed from behind) with the whitish 

 gleam so usual in flies which occur on dry sand, minutely pubescent but not 

 at all ribbed or rippled ; base, stigma, and nteaiastinal vein pale brownish 

 yellow, other veins brown and not very intense ; discal cross-vein distinctly 

 beyond the middle of the discal cell and sometimes placed at about two- 

 thirds of its length ; the three marginal spaces of the wing after the wing-tip 

 almost equal (the middle one being very slightly the narrowest) but the fourth 

 space ( = third posterior cell) only rather more than half as long as the third. 

 Alar squamae large, glassy yellowish with a less glassy margin and a short 

 yellowish fringe. Halteres large and conspicuous, light brown but with the 

 base of the knob only brownish yellow. 



9 . Rather distinct from the male. Head when seen from above more rounded ; 

 frons at the vertex about one-third the vddth of the head and thence steadily 

 widening down to the antenmy where it is nearly twice as wide as at the 

 vertex, suddenly produced from about its middle to the base of the antennae ; 

 the flat upper part of the frons light grey with a slight glistening scale-like 

 yellow inibescence on its middle lower part and a slight sloping longer 

 yellowish pubescence near the sides, and the sides themselves sometimes 

 yellowish ; the produced part of the frons is broadly dull yellowish at the 

 sides and bears there short glistening scale-like j^ellow pubescence, but its 

 middle part is grey and has minute black hairs at its sides, and the blackish 

 grey part of the side-cheeks close to the frons between the antenna and the 



