168 INSECTA, 
Gerais, Lat. 
Where the antenne are filiform, the sheath of the sucker is triar- 
ticulated, and the second pair of legs are very remote from the first, 
and at least double the length of the body *. 
The two anterior legs, as well as in the following subgenus, act as 
pincers. 
Vea, Lat. 
Where the antenne are also filiform, but the sheath of the sucker 
has but two apparent joints, and the legs, much shorter, are inserted 
at nearly equal distances from each other +. 
FAMILY II. 
HYDROCORISA. 
In our second family of the Hemiptera, the antenne are inserted 
and concealed under the eyes; they are shorter than the head, or 
hardly as long. 
All these Insects are aquatic, carnivorous, and seize others with 
their anterior legs, which flex on themselves and act as pincers. 
They sting severely. 
Their tarsi present but one or two joints. Their eyes are in gene- 
ral remarkably large. 
Some— Nepides—have the two anterior legs in the form of pincers, 
composed of a thigh, either very thick or very long, with a groove 
underneath for the reception of the inferior edge of the tibia, and 
of a very short tarsus; or one that is even confounded with the tibia, 
and forming with it a large hook. 
The body is oval and much depressed in some, and linear in others. 
They form the genus 
Nepa, Lin., 
Or that of the Aquatic Scorpions, as they are commonly called, which 
is thus divided : 
Gaxteuuus, Lat., 
Where all the tarsi are similar, cylindrical, and composed of two 
very distinct joints, the last with two terminal hooks. ‘The antennz 
appear to consist of but three joints, the last of which is the largest 
and ovoid t. 
The antenne of the following genera are quadriarticulated, and 
the auterior tarsi terminate simply in a point or hook. 
* Lat., Gener. Crust et Insect., III, p. 131. 
+t Lat. Ib. 
t Lat. Ib., p. 144; Naucoris oculata, Fab. 
