12 
HETEROPTERA. 
a Aquatic (residing- in the water), posterior legs generally ciliated and 
fitted for swimming: antennae very short, concealed in cavities 
beneath the eyes; tarsi rarely more than two jointed. 
b Hind legs elongated, strongly ciliated; head nearly as wideas the body; 
antennae four-jointed; anterior legs not raptorial, placeo nor- 
ma Py ... Notonectidae. 
bh Hind legs not ciliated nor elongated; head small, much narrower than 
the thorax; anterior legs raptorial, placed well forward toward the 
head, like large antennae, having one-jointed tarsi. Nepidcie. 
aa Sub-aquatic (residing on the water or in damp places). 
c Body flat and broadly oval, nearly circular, eyes pedunculated; ante¬ 
rior femora enlarged: tarsi one or two-jointed; beak short; an- 
tennae short and concealed; residing in damp places .G -alguliaae. 
cc Body long and narrow; antennae somewhat long and slender, not con¬ 
cealed; anterior femora nol enlarged; tarsi two or three jointed; 
eyes not pedunculated; residing on the water. Hyarometriciae. 
aaa Terrestrial. 
d Beak consisting of three joints, if four, the first is very short and an- 
nuliform. 
t Beak naked, not received in a channel; head small, narrowed behind 
into a neck; body somewhat elongate; terminal joints of the an- 
tennaae slender. . . 
ee Beak received in a channel; head not narrowed behind into a neck; 
body generally broadly oval: last joints of the antennae not less 
than the preceding... lmgiaae. 
dd Beak consisting of four distinct joints. 
/ Scutellum not reaching back to the middle of the abdomen. 
a Antennae four-jointed, inserted in or below an ideal line extending 
from the eyes to the base of the beak; membrane ot the elytra 
never containing more than five veins. 
h Terminal joints of the antennae very slender, thinner than the preced¬ 
ing- ocelli never present ; the coriaceous part of the elytra with a 
stigma-like triangular piece at the apex; membrane with only 
one or two strong veins .... eapsiaae. 
hh Terminal joints of the antennae not thinner than the preceding, but 
not clubbed; ocelli sometimes present; elytra without the stigma- 
like piece. ‘ 
an Antennae inserted above the ideal liue, terminal joint enlarged, some- 
Qi times elongate and then scarcely enlarged; beak with the third , 
joint shorter than the fourth; ocelli present... 
ff Scutellum large, extending to or beyond the middle of the abdomen, 
sometimes nearly covering it; usually triangular or sub-orbicu- 
lar; antennae sometimes five-jointed. ^....bcuteuenaae. 
PSYLLIDaE (Jumping Plant-lice.) 
As but few species of this family belonging to our American fauna 
have as yet been described, although doubtless many are to be found 
here I will give the family and generic characters, with a little more 
particularity than I should otherwise do. They are similar in appear¬ 
ance to the ordinary plant-lice, but the head is broader and resembles 
somewhat closely the head of a little leaf-hopper; it is short and gen¬ 
erally triangular in front, and usually deeply cleft in the middle ol 
the front; the eyes are lateral and prominent; and, in addition to these 
true eyes* they are usuallv furnished with three ocelli, or little simple 
eves placed on the top of the head in a triangular form, one close to 
the inside of each eye, and one on the middle of the front where the 
cleft or notch commences. The antennae, which are rather long, slen¬ 
der and thread-like, present the most prominent characteristic for dis¬ 
tinguishing the family, in the two little bristles with which each is 
usually furnished at the tip; they are usually ten-jointed, though in 
some species they have but nine or even eight joints and it 1 am not 
mistaken, in one*American species there are eleven;, the basal joint is 
