2. DIALINEURA 583 



or less obvious darkened stripe wliiclL runs from beneatli the base of the 

 antennae slightly downwards to the eyes, and bearing numerous black hairs 

 except on the produced upper angle and not quite to the antennae ; face bare, 

 but the pubescence long and pale yellow beneath the eyes and on the broadened 

 lower part of the back of the head and without any black hairs beneath 

 the eyes (though I have sometimes detected a stray black hair there) ; jowls 

 yellowish white ; back of the head dull yellow, diminishing in width upwards 

 but never becoming flush with the eyes, and the pale yellow pubescence 

 which is long on the lower part becoming almost brownish yellow and shorter 

 on the upper part with a shorn appearance, while on about the middle part well 

 away from the eyes are several (6-10) black bristles, and on the upper third is 

 a postocular row or festoon of about ten or twelve rather long black bristles 

 overhanging the eyes ; vertex rather small and triangular, rather elevated 

 and covered with dull brownish yellow dust, and bearing short inconspicuous 

 forwards-sloping mainly black pubescence. Proboscis large and considerably 

 produced, brown with yellowish coloring near the tip, and moderately 

 pubescent beneath ; palpi protruded, thin, brownish yellow, and bearing con- 

 spicuous long yellow pubescence. Eyes quite bare, practically touching for 

 more than a quarter of the distance between the occiput and the antennae but 

 with a brownish yellow line separating them ; facets all equal. Antennae 

 brownish grey, considerably longer than the head ; basal joint loiig and 

 conspicuously incrassated, more than twice as long as broad and as long as the 

 rest of the antennae, entirely covered with lig-ht brownish grey dust, and 

 bearing all over numerous long black bristles or bristly hairs (more numerous 

 and more scattered than in Thereva) with some finer pale hairs beneath 

 about tlie base ; second joint very short, and bearing numerous short black 

 bristly hairs ; third joint bare and conical but slightly enlarged at its tip, 

 and with a very short terminal triangular style which bears a minute apical 

 arista. 



Thorax brown with a slight reddish tinge and with a pair of widely separ- 

 ated pale stripes, which widen posteriorly but barely reach the hindmargin ; 

 pubescence brownish yellow, but some slightly longer and more erect black 

 hairs are inconspicuously intermixed on the front half of the disc, and these 

 hairs spread out above the suture as far as the dorsopleural suture ; pleurte 

 whitish grey, and bearing pale yellowish pubescence which forms large shaggy 

 tufts on the mesopleurae and metapleurae, and is fairly abundant on the 

 sternopleurae, but leaves the hypopleurae quite bare. Bristles black, usually 

 three praesutural and usually two supra-alar (but both sometimes asymmetri- 

 cal), one large postalar, and two pairs of large praescutellar. Scutellum 

 similar to the thorax in colour, but the pubescence longer, paler,_ and more 

 conspicuous, and with two pairs of not very long almost straight black 

 marginal bristles. 



Abdomen long and conical, entirely covered with silvery white dust and 

 moderately long pubescence, which is more recumbent on the disc than at the 

 sides ; not a single dark colored hair is visible on any part of the abdomen. 

 Belly obscured by similar whitish dust and with all the hindmarginal hems 

 whitish yellow; pubescence erect but not nearly so abundant as dorsally, 

 though still all white and fairly conspicuous. Genitalia covered with whitish 

 grey dust ; upper basal plate large and bearing rather long pale yellow 

 pubescence (with two small rounded pale brown lamellae extending from 

 beneath its end), arched and curving over towards the lower lamellae, which 

 are blackish (or dark orange), long, narrow, and bear long pale pubescence ; 

 inner processes brownish orange. 



Legs dull blackish but obscured by grey dust, with just the tip of the 

 femora dull orange as well as all the tibiae except just the blackish tip ; tarsi 

 obscurely orange from the base to rather more than half-way through the 

 second joint and after that only obscurely brown ; coxae all covered with 

 whitish grey dust and bearing long greyish white pubescence ; trochanters 

 shining black at the tip and almost bare, but the hind pair with some erect 

 pale pubescence. Pubescence behind and beneath the anterior femora 

 whitish, and these femora with scaly adherent whitish pubescence on the 

 upper part ; hind femora with but little hairy pubescence except beneath on 

 the basal half, though they bear scaly adherent whitish pubescence all over 



