58 SPIDER FLY ; GROUSE FLY. 



The bearded hair, first, I believe, observed by De Geer, and re- 

 corded by him as found on this O. ovicnlana, was very noticeable. Of 

 this lie remarked in liis paper (referred to below*) on the " Hipp<>- 

 bosqin' verd," Hippubosca (now OnutluDitijia) avicularia, Linn.: — 



" Between the ' pcloiies ' " [pads or pulvilli] " there is placed a very 

 remarkable bearded hair, having bristles on each side like a little 

 feather, which is attached beneath the foot. We have already men- 

 tioned that the Uippohosca have a similar hair appended to their 

 tarsi." — (C. De G.) 



This bristly hair will be found figured nt p. 53, and also in the 

 Plate at frontispiece, as seen on the feet of the Forest Flies of the 

 New Forest ; m the case of Mr. Wheler's Grouse Fly, the hair was 

 more curved in different directions, and the side hairs (as seen) were 

 longer and fewer in number ; but, as previously observed, the amount 

 to which the side hairs are observable depends to some degree on the 

 nature of the medium in which they are displayed. 



I also noticed, amongst the appendages of the claws of this Grouse 

 Fly, the very peculiar structure, figured in the frontispiece, at the 

 base of the claws, as a flat membrane, with a series of slightly curved 

 tubes, or ridges (much resembling what are sometimes known as 

 "pseudo-tracheffi "), on each side of a central longitudinal vein, or 

 tube. In H. equina this membrane is in connection with a bulb-shaped 

 organ covered with what appear to be short hairs, which is also 

 figured in the Plate above referred to, and which I have described at 

 p. 101 of my Nineteenth Annual Eeport, but which I believe had not 

 previously been observed, nor do I know its uses. In the Grouse Fly, 

 as the specimen had not been specially displayed for figuring, I was 

 unable to get a view of the bulb, and, should it be feasible further on 

 in the year, it would be of interest to obtain specimens which would 

 supply material for a fully detailed representation of the claw of 0. 

 aoicnlaria with all its appendages. 



The colour of the fly is very variable, being noted as sometimes of 

 a horn-yellow, sometimes brown or brownish above, and again, in 

 some cases, the lighter parts are entirely green. The wings are tinged 

 with brown, and longer than the abdomen. + The body and legs are 

 bristly and hairy. 



The flies are not uncommon, and are parasitical on birds, but 

 often wander to human beings, and settle in the hairs of the head 

 and beard. 



Some of the different kinds of wild birds which are mentioned by 



* 'Memoires pour servir a I'histoire des Insectes,' par M. le Baron Charles 

 De Geer, vol. vi. p. 288. 



t For detailed description of neuration of the wings of the genus Oniithomyia, 

 see Schinei's work, previously referred to, part ii. p. 646. 



