460 MOTIONS OF INSECTS. 
particularly those of B, fascicularis. A Brazilian beetle in my cabinet, 
belonging to the family of the Clerid@, but not arranging well under any of 
Latreille’s genera, which I have named Priocera variegata, has curious in- 
voluted suckers on its feet. The strepsipterous genera S/ylops and Xenos 
are remarkable for the vesicles of membrane that cover the under side of 
their tarsi, which, though flaccid in old specimens, appear to be inflated in 
the living animal or those that are recent. It is not improbable that these 
vesicles, which are large and hairy, may act in some degree as suckers, 
and assist it in climbing. 
The insects of the Orthoptera order are, many of them, remarkable for 
two kinds of appendages connected with my present subject, being fur- 
nished both with suckers and cushions. The former are concayo-conyex 
processes, varying in shape in different species, being sometimes orbicular, 
sometimes ovate or oblong, and often wedge-shaped, which terminate the 
tarsus between the claw, one on each foot. They are of a hard substance, 
and seem capable of free motion. In some instances*, another minute 
cavity is discoverable at the base of the concave part, similar to that in 
Cimbex lutea’ The latter, the foot-cushions, are usually convex appen- 
dages, of an oblong form, and often, though not always, divided in the 
middle by a very deep longitudinal furrow, attached to the under side of 
the tarsal joints. Sir E. Home is of opinion that the object of these foot- 
cushions is to take off the jar when the body of the animal is suddenly 
brought from a state of motion to a state of rest. This may very likely 
be one of their uses ; but there are several circumstances which militate 
against its being the only one. By their elasticity they probably assist the 
insects that have them in their leaps; and when they climb they may in 
some degree act as suckers, and prevent them from falling. But their use 
will be best ascertained by a review of the principal genera of the order. 
Of these the cock-roaches (Blatta), the spectres (Phasma), and the pray- 
ing insects (Mantis), are distinguished by tarsi of five joints. The grass- 
when it immediately began to rub the pulvilli against the tarsal brushes ; but om 
replacing them on the glass they adhered as closely as before, and it was only by 
efforts almost convulsive, and which seemed to threaten to pull off its limbs from 
its body, that it could succeed in moving a quarter of aninch at a time, After 
watching it with much interest for five minutes, it at last by its continued exertions 
got its feet released and flew away, and alighted on a curtain, on which it walked 
quite briskly, but soon again flew back to the window, where it had precisely the 
same difficulty in pulling its pulvilli from the glass as before; but.after observing 
it some time, and at last trying to catch it, that I might examine its feet with 
lens, it seemed by a vigorous effort to regain its powers, and ran quite actively on 
the glass, and then flying away I lost sight of it. I am unable to give any satis- 
factory solution of this Pipe fact. The season, and the fly’s final activity, 
preclude the idea of its arising from cold or debility, to which Mr. White attributes 
the dragging of flies’ legs at the close of autumn. The pulvilli certainly had much 
more the appearance of adhering to the glass by a viscid material than by any 
pressure of the atmosphere, and it is so far in favour of Mr, Blackwall’s hypothesis 
on which one might conjecture that from some cause (perhaps of disease), the hairs 
of the pulvilli had poured out a greater quantity of this viscid material than usual, 
and more than the muscular strength of the fly was able to cope with, 
1 Kirby in Linn, Trans, xi. 106. t. viii. f. 13. a. 
2 I observed this in the hind legs of a variety of Locusta migratoria, 
5 Philos. Trans. 1816., 825, t. xix. f. 5. 
4 Thid. p. 825. P 
5 In a specimen in my cabinet of Blatta gigantea, the posterior and anterior tarsi 
