Brachypalpus. 505 



than thorax, a little narrowed behind. Genitalia relatively large. Legs 

 with the hind femora considerably thickened and with short, strong 

 spines below; hind tibiæ somewhat compressed and curved; hind 

 trochanters in the male with a short, conical process on the inside. 

 Wings with the medial cross-vein after the middle of the discai cell, 

 somewhat oblique; the base of the radial vein with fine hairs; stig- 

 matical cross-vein indistinct. Squamulæ as in the allied genera. 

 Plumula with simple hairs. 



The developmental stages are not described, but Bremi notes 

 (Isis 1846, 174) that the has found the larva of B. valgus in decaying 

 wood in willows. 



Of the genus 7 species are recorded from the palæarctic region, 

 but, as remarked below, the species are not well characterised ; one 

 has been found in Denmark. 



1. B. laphriformis Fall. 



1816. Fall. Dipt. Suec. Syrph. 22, 11 (Syrphm). — 1862. Gerståck. Troschel 

 Arch. 1862, 28, II, 473. — 1907. Kat. palåarkt. Dipt. III, 127. — Xylota 

 valga Zett. (nec Panz.) 1843. Dipt. Scand. II, 868, 1 et 1849. VIII, 3191, 1. 



Male. Vertex brownish black, frons whitish pruinose, just above 

 the antennæ bare and shining; epistoma black with only the lower 

 front part yellovv, or it is yellow also on the sides up to the eyes so 

 that only a spot below the antennæ and the lower side parts are 

 black, but the colours are obscured by white pruinosity ; the lower 

 front part and the lower side parts bare ; to each side of the antennæ 

 is a blackish streak across to the eye. The vertex has long, black 

 hairs, frons bare only with yellow hairs along the eye-margins, and 

 epistoma likewise with only a few pale hairs along the eye-margins; 

 the epistoma is hollowed below the antennæ, without central knob 

 but with the front mouth edge produced about equally with the 

 frontal prominence; it is somewhat but not very descending. Occiput 

 yellowish grey pruinose, the hairs whitish below and long to up above 

 the middle, yellow above, and here also some black hairs. Antennæ 

 brownish or reddish brown, arista brown, palest at the ape??. Thorax 

 blackish æneous, shining, somewhat pruinose at the front and side 

 margins; it is clothed with long, somewhat dense, yellow or reddish 

 yellow hairs, on the middle some black are intermingled. Scutellum 

 unicolorous with thorax and with similar but longer hairs. Pleura 

 yellowish pruinose, with long, yellow hairs. Abdomen elongate, about 

 of the breadth of thorax, a little narrowed behind; it is black and 

 shining; the first segment is yellow but often greyish pruinose on the 

 disc, the second segment yellow at the side margin ; the segments have 



