a 
ee 
INSECTA. 439 
drum-membrane (La timbale, 1. 1. figs. 5, 6, 9,114, ¢), which is moved 
by a very strong muscle arising from the partition mentioned above. 
When these muscles contract powerfully on each side and then 
suddenly relax, a vibratory motion arises, producing a sound which 
is swelled by an air-vesicle, a vesicular trachea, that lies near the 
drum. The sound is the so-called song of the cicada, which is 
peculiar to the males, whence Xenarcuus extolled the fortune of* 
these animals, whose wives are dumb. 
The so-named manna, not to be confounded with that which 
served the Israelites for food in the Arabian desert, is an exudation 
from ash-trees in consequence of the puncture of the Cicada orni. 
Sp. Cicada orni L., Reset, Jns. 1. Locustar. Tab. xxv. fics, 1, 23) Tab, 
XXVI. figs. 3,5; BRANnpT and RatTZEBURG, Mediz. Zool. 11. Tab. xxvt. figs. 
I—4 ;—Cicada fraxini, Tettigonia Fraxini Fasr., Ra@seEt, ibid. Tab. xxv. 
fig. 4, XXVI. fig. 4, figs. 6—8, from the south of France, Italy, &e. 
Section I. Heteroptera. Elytra coriaceous at the base, mem- 
branous at the apex. Rostrum frontal, rising from the anterior part 
of the head. 
The insects~of this division are the only ones properly to which 
the name of hemiptera is applicable. Some amongst them suck the 
blood of other animals; others live, like those of the preceding 
division, on the juices of plants. The anterior segment of the 
thorax is much larger than the other two. The antenne have 
never more than five and ordinarily only four joints. 
Comp. on this division F. L. pr ta Porte, Essai d’une classification 
systematique de Vordre des Hemiptéeres ; GuéRIN, Magas. de Zool. 1832, Ins. 
Pl. 51—s5. 
Family XXXVIII. Hydrocorise. Antenne inserted under 
the eyes, recondite, shorter than head or scarcely of length of head, 
three- or four-jointed. Tarsi mostly biarticulate. Eyes mostly 
large. Rostrum short. 
Water-bugs. They live in fresh-water. In the following family 
also are some species which live in water, but which do not swim as 
these do, with the exception of the genus Galgulus Latr., which 
Westwoop refers to the Geocorise. 
I. Ocelli none. 
A. Two anterior feet recurved downwards, with thighs not in- 
crassated ; two posterior long, pilose, natatory, sometimes destitute 
