692 EXTERNAL ANATOMY OF INSECTS. 
in others (Balaninus Nucum, &c.) a pair only on the 
penultimate joint ; in Cordylia Palmarum, Rhina barbi- 
rostris, &c., that joint has an intire cushion; in ELuryno- 
tus muricatus* the three first joints of the four anterior 
tarsi are similarly circumstanced, but the cushions re- 
semble sponge °. 
The second kind of cushion is a vesicular membrane 
capable of being inflated. This distinguishes the tarsi 
of Thrips °, and many mites ¢; likewise those of Xenos*; 
and also of many Orthoptera fully described on a former 
occasion f, though the fact of their capacity of inflation 
has not been ascertained, belong to this section. 
The third kind of covering of the sole is when the 
three or four first joints of the tarsus each terminate in 
one or two membranous lobes or appendages : of the first 
description is Priocera, in which the lobes are involute &; 
and of the second Rhipicera *, in which there is a pair on 
each joint, in the Brazil species set with very fine hairs. 
The fourth and last kind are what may with the utmost 
propriety be denominated suckers, since their use as such 
is clearly ascertained. ‘These are not only to be found 
in a large proportion of the Diptera, in some of which 
there are ¢wo of them, as in the Aszlzde@‘; and in others 
three, as the Tabanide*; but also in many of the subse- 
quent Orders: thus, in the Heteropterous Hemzptera, in 
Scutellera and Pentatoma, but not in the Reduviada, and 
* Linn. Trans. xii. t. xxii. f. 1. > For other instances of 
this structure, see above, p. 335. ° De Geer, iii. 7. 
4 Ibid. vii. 84. Pirate XXVII. Fre. 60, 63. 
e Ibid. Fie. 61. f Vor. I. p. 323—. 
& Pirate XXVIL. Fic. 59. h Linn. Trans. xii. t. xxi. f. 3. 
* Prate XXVII. Fic. 53. 
« Ibid. Pie, 54, Philos. Trans. 1816. ¢. xviii. f. 9—11. 
