^Jo\S!jlnw^^^^^^ PKOCEEDING-S OF SOCIETIES. 65 
It was in contimiation of a paper read before the Society in 
December, 1867, and began by remarking upon the unsatisfactory 
character of the mounted slide of the proboscis, as usually sold, which 
from its flattened arrangement gives a very inaccurate idea of the real 
organ. The writer suggested that in order to gain a better idea of the 
object, the fly itself should be soaked in Liquor Potassse for a week or 
so, and then viewed, under the dissecting microscope, when lying on 
its side in a drop of clear water. This will show the various parts 
in profile, and in their relative position. Then cutting off the entire 
head, let it be placed on a slide, in a drop of water, with the compound 
eyes upwards, so that the front, and not the top of the head may be 
seen. Being then pressed by a dry slide, the proboscis will be exserted, 
the lobes everted, and the natural position of the palpi will be seen to 
be very different from that which the mounted slide seems to present ; 
for while that shows the two chitinous "straps," or fulcra, as apparently 
binding down the palpi, the palpi are really above them. 
After referring to the probable nature of these fulcra, the writer 
described the teeth, which may be seen at the bases of the ten 
furrowed channels, and arranged three-deep, making thirty on each 
side. These seem to be unnoticed in descriptions of the proboscis. 
They are long, formidable, two-pronged organs, free anteriorly, and 
may be made out in the mounted slide ; but there they appear to be in 
the same plane with the lips ; whereas in nature they are not so. The 
arrangement and number of these teeth seem to vary in different flies, 
for while the blowfly has three rows, in Musca domestica there appears 
to be but one. 
The spinnerets of Epeira diadema were described as consisting of 
three pairs of somewhat conical processes. The front pair are trun- 
cated cones, the summits alone being provided with spinnerules, but 
of three different sizes; one set very small near the interior edge, 
others of medium size near the centre, and one very large spinning 
tube on the inner margin. The middle pair of spinnerets are pro- 
fusely furnished with very long spinnerules, amongst which are three 
very large ones near the centre and two at the upper part, with three 
or four of intermediate size. The hinder pair are provided with 
spinnerules on the summits and sides, and have, each, four of the larger 
kind, one low down, and the other three, together, towards the top. 
Careful observation of the spider at work seems to show that the front 
spinnerets are used for attaching and forming the guy lines and radial 
threads of the web ; the small spinnerules forming the looped attach- 
ments and the filaments from the mediiun spinnerules coalescing 
around the thread from the large spinning tube; while from the 
small spinnerules of the hind pair proceed the broad bands of web 
with which the spider's victim is swathed ; the four larger ones pro- 
bably yielding the strong cords by which the prey is dragged along. 
The central pair are probably employed in furnishing the dotted spiral 
lines. 
The points referred to, and the varying forms of proboscis in 
different flies, were illustrated by mounts in jelly in deep cells. 
