13 
usually thick, and in one genus the second joint is greatly dilated. 
The beak is short and three-jointed, arising almost between the fore¬ 
legs. The hind margin of the sternum or breast usually terminates on 
each side with a little spine. The wings, which occur in both sexes, 
are four in number, and when at rest are placed over the abdomen in 
the form of a very steep roof; the front pair have a strong mid-rib or 
mid-vein, running through the middle and dividing near the center in- 
Fig-. 2 . to three principal branches, each of 
which is usually further divided into 
two branches; the veins of the hind 
wings are quite slender. (See Fig. 2.) 
The abdomen of the females is ter¬ 
minated by a conical ovipositor, and 
in the males is usually furnished with 
several short, erect appendages; but 
in neither do we find the corniculi 
or honey-tubes, so common in the true 
psyllapyri. aphides. The tarsi, as before stated, 
are two-jointed; and all the species possess the power of leaping, like 
the leaf-hoppers, hence the generic name, Psylla , which was the Greek 
name for a jumping insect, was given to them by Geoffroy. Their 
general habits are very similar to the leaf-hoppers, with which, in this 
respect, they appear to be closely allied. 
They subsist, in all their stages, upon plants; and the species are 
doubtless very numerous, although but few, as before stated, have 
been described in this country. The larva? have the body quite 
flat, the head broad, the abdomen rounded, and the antennae, at first, 
apparently one-jointed; the pupae show the rudimentary wings, in 
the form of four, comparatively large, broad scales, attached to the 
sides of the thorax. Many of the species are covered, during the 
larva state, with a delicate cottony substance, usually arranged in 
flakes; though some, as our most common species, are naked. A few 
species, as for example one . which inhabits the hackberry, form galls, 
in which they reside. ' 
The species, so far as I am aware, without any exceptions, deposit 
eggs, from which the young are hatched, and do not bring forth liv¬ 
ing young as do most of the true aphides. 
The characters, therefore, by which we may distinguish them from 
the aphides, are as follows: 
The two little bristles at the tip of the antennae, their habit of 
leaping, the form of the head, and the veining of the wings. 
The family has been divided into quite a number of genera, some 
of which depend on very slender characters, but at present we shall 
have occasion to refer only to two or .three of these. 
Genus DIRAPHIA. 
There are no common names by which to distinguish this or other 
generic groups from each other. I am unable to give at present, the 
full Characters of this genus, which, I believe, was established by M. 
Waga, but as it was originally included in Livid , with which it is 
