210 Descriptions of British. Diptera. 



equal. Legs yellow, the tarsi dark-brown. 4^ lines ; proboscis about 

 half that length. 



" Devon, Mr J. Cocks, and near Perth," Curtis' Brit. Ent. " Do- 

 ver, July 1826." Mr Jngpen. 



BOMBYLIUS CINERASCENS. 

 Mikan, Monog. pi. iii. Fig. 10 ; Meigen, ii. 212. 

 This small species, which, according to Mr Stephens, has oc- 

 curred in Britain, is thus described by Mikan, to whom we are 

 indebted for a monograph of this tribe of Diptera : whiskers black 

 above, grey beneath : body black, covered throughout with ash- 

 grey hairs ; wings transparent, the base black : halteres black : 

 thighs with grey pubescence ; tibiae brown ; tarsi black. 2| lines ; 

 proboscis If. 



Genus— PHTHIRIA. 



Antennae somewhat shorter than the head, approximating at the 

 base, and directed sideways ; first joint short and cylindrical, with a few 

 hairs on the outer side ; second cup-shaped and slightly pubescent; 

 third fusiform and compressed, nearly double the length of the two 

 others taken together, and having a very short bifid style at the apex ; 

 proboscis at least as long as the head and thorax ; labrum grooved 

 beneath ; palpi thick and club-shaped, concealed within the cavity of 

 the mouth: head spherical, the forehead prominent; ocelli three; ab- 

 domen obtusely conical : wings of moderate size, the submarginal 

 cells nearly straight ; first posterior one open ; anal cell closed at the 

 extremity and slightly petiolated : legs long and slender. 



This genus includes a few small insects which were formerly re- 

 ferred to Usia of Latreille and Volucella of Fabricius. " The prin- 

 cipal relations which they have with the Bombylii," says Mac- 

 quart, " consist in the length of the proboscis, the approximation 

 of the antennae at the base, and in the form of the third joint of these 

 organs; but more considerable differences give them a peculiar ha- 

 bit, and render their affinity liable to be misunderstood. The sphe- 

 rical form of the head, and conical shape of the abdomen, the short- 

 ness of the first joint of the antenna?, and finally the reticulated ap- 

 pearance of the wings, remove them more or less from the bombylii: 

 in the latter character, indeed, they deviate from the greater part 

 of the family. The nervures are not sinuous as in Anthrax and 

 Mulio ; the first cell of the hinder border is not closed as in the 

 Bombylii ; and the anal cell, contrary to what takes place in the ge- 

 nus just named, is closed at its extremity, as in Usia and Geron. 



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