﻿114 ERNEST E. AUSTEN — NEW AFRICAN 



Looking like a small Tabanus, and in general appearance, and especially in its 

 abdominal markings, presenting a deceptive resemblance to Silvius decipiens, Lw. } 

 from ivhich it differs in the general ground-colour of the dorsum of the abdomen, in the 

 icings being tvithout a dark and sharply defined stigma, and, in the female sex, in the 

 eyes being less distinctly hairy, in the front being longer, and in the frontal callus not 

 extending to the eyes. — Eyes densely hairy in $, microscopically hairy (under an 

 ordinary hand-lens often appearing bare) in Q ; dorsum of thorax slate-black" in $ , 

 slate-coloured, dark brown, dark chestnut-brown, or reddish-brown in Q , with grey 

 longitudinal stripes (shorter and less conspicuous in $ ) i- n both sexes ; dorsum oj 

 abdomen cinnamon-rufous or dark chestnut-brown {in $ with a broad, black median 

 longitudinal stripe on second to fourth segments inclusive, and distal extremity clove- 

 brown), with a double series of rounded or transversely elongate spots (especially 

 large and conspicuous in Q), hind borders of segments, and a median series oj 

 triangles resting on latter smoke-grey or drab-grey ; wings hyaline. 



Fig. 1. — Silvius fallax, Austen, $> • X 4. 



Head, except vertical triangle in $ and frontal callus and area surrounding 

 ocelli in Q, light grey pollinose ; when denuded, face and jowls in both sexes and 

 sub-callus in Q fawn-coloured ; vertical triangle in $ and area surrounding 

 ocelli in Q clove-brown ; frontal callus in Q chestnut or burnt-umber coloured, 

 large, narrowly separated from eye on each side, more or less quadrate in outline, 

 but with rounded angles ; face, jowls, and basi-occipital region clothed with 

 whitish hair, in $ outer border of face, jowls, and basi-occipital region clothed 

 with dark brown or brownish hair ; eyes in $ densely clothed with fine grey 

 hair, and rather more than their upper halves (except hind borders) consisting of 

 larger facets than elsewhere ; palpi ochraceous-buff, clothed with whitish hair, 

 which on upper surface of terminal joint in tf is often intermixed with dark hair ; 



* For names and illustrations of colours, see Ridgway, " A Nomenclature of Colors for 

 Naturalists," (Boston : Little, Brown & Company, 1886.) 



