INSECTA. 



439 



drum- membrane (La timbale, 1. 1. figs. 5, 6, 9, 11 t, t), 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 cicadce, which is 

 peculiar to the males, whence XENARCHUS 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., ROSSEL, Ins. n. Locustar. Tab. xxv. figs, i, i, Tab. 

 xxvi. figs. 3, 5 ; BEANDT and KATZEBUEG, Mediz. Zool. n. Tab. xxvi. figs, 

 i 4 ; Cicada fraxini, Tettigonia Fraxini FABB., KCESEL, ibid. Tab. xxv. 

 fig. 4, xxvi. fig. 4, figs. 6 8, from the south of France, Italy, &c. 



Section II. Heteroptera. Elytra coriaceous at the base, mem- 

 branous at the apex. Rostrum frontal, rising from the anterior part 

 )f 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 antennae have 

 never more than five and ordinarily only four joints. 



Comp. on this division F. L. DE LA POETE, Essai d'une classification 

 systematique de I'ordre des Hemipteres; GUEBIN, Magas. de Zool. 1832, Ins. 

 PI- 51-55- 



Family XXXY1II. Hydrocorisce. Antennae 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 LATH., which 

 WESTWOOD refers to the Geocorisce. 



I. Ocelli none. 



A. Two anterior feet recurved downwards, with thighs not in- 

 crassated ; two posterior long, pilose, natatory, sometimes destitute 



