260 QUARTERLYJOURNAL. ' 



The LEGS are whitish or very pale yellow, long and slender, of a 

 cylindrical fornfi, and of nearly the same diameter through their en- 

 tire length. The coxae (small joints by which the femurs are con- 

 nected with the sternum), as they are directed more or less back- 

 wards, vary the point from which the legs seem to arise in different 

 specimens when viewed from above. The femurs, tibias, and second 

 joint of the tarsi, are all of about the same length. The third, fourth, 

 and fifth joints of the tarsi (Plate 5, fig. g), are successively shorter ; 

 whilst the basal joint is the shortest of all, its length little exceeding 

 its diameter. 



All parts of the body and limbs are clothed with minute, slender, 

 longish hairs. 



The MALE differs so remarkably in its aspect from the female, 

 and is moreover so rare an insect, that it has generally escaped ihe 

 researches of observers. It would appear from Mr. Curtis's paper, 

 that Meigen is the only one who has identified and given a descrip- 

 tion of this sex ; and I should distrust my having any specimens of 

 it, but that one of the flies hatched from the larvas already spoken 

 of as gathered in a wheat-field early in the spring, is a male (Plate 

 5, fig. 4) ; and a few of my other specimens manifestly coincide 

 with this. In these the antenncE are at least double the length of the 

 body, and composed of twenty-four joints of a very exact globular 

 form ( Plate 5, fig. e ) ; each joint encircled with a single row of 

 hairs, and separated widely from its fellows, the thread between 

 being of about twice the length of the joint itself. The abdomen, in- 

 stead of being of an ovate form, as in the female, is broadest at the 

 base, and thence tapers gradually, though slightly, towards the 

 apex ; the terminal segment, however, being broader than the one 

 or two preceding it, and of a reniform shape, with the lobes directed 

 backwards. The male is also somewhat smaller in size : in all its 

 other marks, it appears to correspond with the female. 



Among the hosts of specimens of the female that may be met 

 with, there will occur considerable variations in size, color, and 

 some minor particulars. The common length, to the tip of the ab- 

 domen, is the twelfth of an inch, or slightly under this ; yet I have 

 measured recent specimens from the wheat-field, that were but hall 

 this size. The color seems to be more uniform in specimens taker 

 from the wheat-field, than in those procured in other situations. It is 

 of a lively orange-red, particularly upon the abdomen, where the 



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