TO THE FEET OF INSEOTS. 27 
Those presented by Pterostichus were then somewhat minutely 
described, as the largest the author had had the opportunity of 
observing whilst living and in action. They may be considered 
as composed of two portions: the first is an elastic membrane, 
perfectly smooth on the lower surface to admit of its exact adapta- 
tion ; the second, on which the former is borne, is a long stem or 
pedicle arising at an oblique angle from the tarsal joint, and bent 
suddenly downwards near its insertion into the membranous 
portion, by which the latter is rendered capable of being brought 
into contact through its whole extent with the surfaces to which 
itisapplied. In the beetle in question the membrane is reniform, 
with its long axis directed transversely. -Amara was then noticed 
as possessing similar organs, with some of the Carabi; it appeared 
that, as a general rule, their number was increased as their size 
diminished. The presence of scale-like hairs on the back of these 
membranous expansions in some cases was mentioned as affording 
a clue to the condition in Oarabus, where irregular elevated 
wrinkles simulate such corrugations as would be produced by the 
contraction of a membranous tube. 
The structure of these expanded membranous organs was shown 
to agree in every respect with that of true hairs—as being hollow 
for some distance, seated in a depression of the integument on a 
slight papilla, and shut off from the cavity of the joint by a delicate 
membrane, to which some fibres (including probably a nerve) could 
be traced. These statements were borne out by examinations of 
the parts in Carabus and Dyticus, whence the scarcely expected 
result was obtained that the “suckers ”’ of the latter are themselves 
only hairs still more modified. 
Various forms of these spathulate hairs, and plans of their 
arrangement on the tarsi, were mentioned, with the different insects 
on which the author had met with them. 
The strong resemblance in the structure of the bilobed Dipte- 
rous pulvillus to the almost equally cleft third joint in Curculio 
and Chrysomela, which are both furnished with these spathulate ap- 
pendages, led the author to throw out the suggestion that the former 
was, in a homological sense, a modified joint. The principal diffi- 
culty in accepting such a view (namely, the position of the claws) was 
combated by showing that the latter are themselves only modified 
hairs, usually converted into hooks to serve a special purpose*. In 
* Since the above was written, the author has had the opportunity of examin- 
ing the feet of the Ephemera in the living fly, and has ascertained the curious 
fact, that whilst one of the ungues remains in its normal condition as a strongly 
curved, horny hook, the other is converted into a soft fleshy sucker. 
