HETEROPTERA. — HYDROMETRIDE. 467 
of the antenne, by the long and fine spines with which the fore legs 
are armed, and especially by the very short and curved rostrum, also 
spined, which appears to connect this genus with the Reduviide. 
There are three species, found in France and Spain, described by Du- 
four (Annales Soc. Ent. de France, tom. ii. and iii.) ; I likewise possess 
a new species, discovered by M. Van Heyden on the top of a moun- 
tain near Ems, under stones in dry places; as well as another unde- 
scribed species from the banks of the Nile, given to me by Dr. Klug. 
(See the Crochard ed. Regne An. pl. 93. for excellent figures of 
several of these genera. ) 

The fifth family, HypRoMETRID#*, is composed of species differing 
in their habits from all the other Heteroptera ; being constantly found 
upon the surface of standing or running waters, on which they possess 
the power of progression as completely as any of the others.t The 
body is long, narrow, and generally clothed on the under side with a 
fine coating of plush, evidently serviceable in repelling the action of the 
water ( fig. 120. 6. Hydrometra Stagnorum ; 2. Gerris Paludum) ; the 
head generally as broad as the thorax ; the antenne long, slender, and 
4-jointed, the terminal joints not being thinner than the preceding, and 

* Bretioar. Rerer. TO THE HyproMeETRIDA. 
Schummel. Versuch. der Ploteres. 8vo. Bresl. 1882. 
Eschscholtz. Entomographien. (Halobates. ) 
Dufour, in Annales Soe. Ent. de France, vol. ii.; and in his Réchereh. Anat. 
Hemipt. 
Westwood, in Ann. Soc. Ent. France, 1834. 
And the general works of Burmeister, Spinola, Curtis, Dufour, Hahn, Guérin. 
Fabricius, §¢. 
+ Hence Latreille formed them into a distinct section named Ploteres (although 
their motion is not that of swimming), in the Genera Crustaceorum, &c., which 
name L. Dufour changed to Amphibicorisa, a name surely inapplicable, the species 
living neither on the land, or in the water. Burmeister names them Hydrodromici, 
altering the names of Gerris and Hydrometra, overlooking the fact that Cimex lacus- 
tris was given by Fabricius as the real type of his Gerris ( Ent. Syst. tom. iv. p. 187. 
1794), and that C. Stagnorum is Latreille’s type of his genus Hydrometra ( Précis, 
p. 86. 1796), which last Fabricius subsequently (in Syst. Rhyng.) misapplied to the 
genus he had previously named Gerris, which name he then gave te totally dif- 
ferent insects. 
HH 2 
