STRUCTURE OF FOOT OF FOREST FLY. 101 
hardly be attained, but the presence of a hairy bristle is very 
obvious. 
In the course of my own observations of method of progression of 
the fly, I noticed what appeared to be a great peculiarity in its method 
of adhesion to vertical surfaces, and on minute examination such a 
complicated structure of the lower portion of the foot, that, as I was 
unable to find description of this in works to which I had access, I 
took the opportunity of having the foot figured so as to give all 
the details clearly, excepting that the structure being so thin and 
transparent that it was easily pressed somewhat from its right position 
by the covering glass of the slides. Therefore the figures are taken 
(respectively) both from above and as a side-view to show the position 
of the various parts clearly. 
On watching the procedure of the Forest Flies when confined in a 
small cardboard box with upright sides, and a glass cover which 
allowed of observation of their movements through hand-magnifiers 
up to two-inch focal power, I could not perceive that they made any 
use of their strong curved claws to help them in the ascent of the 
vertical sides. Where I could gain a good view, the claws were thrown 
up so as to be clear of any attachment at all, and the fly progressed 
upwards, apparently holding on by the thick basal part only. The 
position would be precisely shown by placing the wrist (in our own 
case) firmly down on any flat substance and raising the hand and 
fingers at an obtuse angle; and on investigation I found a small 
appendage, which, when properly displayed, proved to be the thin 
broad membrane, with plume-like channels or ridges, curving from 
each side of a central vein or tube, and with a bulb thickly covered 
with what appear to be short hairs, which is figured in the two Plates. 
In the view from above, this flap and bulb are in their correct 
central positions; in the other they are pressed to one side; but the 
connection between the flat plume-like flap and the bulb are clearly 
given, as also what appear to be several openings (circular orifices) at 
the summit of the central (?) tube. 
The general appearance of this plume-like broad membrane will be 
seen at first glance to bear a most marked resemblance to the flexible 
lobes, known as labelle, which form the terminal portion of the pro- 
boscis of the Blue-bottle Fly.* 
Of this (the flexible lobes), the author of the work remarks at 
p. 192 :—** These will of course be closed up like the leaves of a book, 
and not opened out as seen in the photograph. . . . Hach lobe con- 
tains about thirty channels, some of which spring from an inner 
marginal tube on each side, and all are open to the air by a narrow 
* See figure, much magnified, given in ‘Our Household Insects,’ by Edw. A, 
Butler, B.A., B.Sc., plate ii. 
