284 [Senate 
length. The coxa; (small joints by which the femurs are connected 
with the sternum), as they are directed more or less backwards, vary 
the point from which the legs seem to arise in different specimens when 
viewed from above. The femurs, tibiae, and second joint of the tarsi, 
are all of about the same length. The third, fourth, and fifth joints of 
the tarsi (Plate 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 the 
researches of observers. It would appear from Mr. Curtis’s paper, 
that Meigen is the only one who has identified and given a description 
of this sex j and I should distrust my having any specimens of it, but 
that one of the flies hatched from the larvae already spoken of as 
gathered in a wheat-field early in the spring, is a male (Plate, fig. 
4); and a few of my other specimens manifestly coincide with this. 
In these the antenna are at least double the length of the body, and 
composed of twenty-four joints of a very exact globular form (Plate, 
fig. e .); each joint encircled with a single row of hairs, and sepa¬ 
rated widely from its fellows, the thread between being of about twice 
the length of the joint itself. The abdomen , instead of being an ovate 
form, as in the female, is broadest at the base, and thence tapers gradu¬ 
ally, though slightly, towards the apex; the terminal segment, how¬ 
ever, 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 abdomen, is the 
twelfth of an inch, or slightly under this; yet I have measured recent 
specimens from the wheat-field, that were but half this size. The 
color seems to be more uniform in specimens taken from the wheat- 
field, than in those procured in other situations. It is of a lively orange- 
red, particularly upon the abdomen, where the color is most observed ; 
but varies from that to amber or honey-yellow, lemon-yellow, and 
even to a cream-color. The specimens already spoken of as having 
