26 
Abdomen . 
The abdomen or hinder division of the body usually shows some¬ 
what distinctly the segments or rings of which it is composed, it is 
generally much the largest of the three divisions of the body, and usually 
oval or ovoid in shape and convex. From the posterior portion (sixth 
segment) in very many species, at each side arises a lit¬ 
tle cylindrical horn, or more properly speaking, tube, as 
it is*perforated. (See Fig. 8) These have received vari- 
ous^names, as honey tubes , cornicles, nectaries , etc. I 
use the first. In some species they are nearly equal in 
length to one-third the length of the body, in others a 
little shorter, and°so on until they are but mere tubercles, while in a 
number of species they are entirely wanting. These and other differ¬ 
ences in these organs furnish generic and specific characters. i hey 
are called honey tubes because it is believed, and perhaps correctly, 
that honev dew is extruded from them. l’hey are considered . long 
when thev exceed in length the distance from their base to the tip of 
the abdomen; medium when they about equal this distance; short when 
their length is less than this distance; and tubercular when their length 
is less than their diameter.. 
Thev are usuallv cylindrical or slightly enlarged at the base, but m 
many species are enlarged or slightly swollen towards the tip. 
The tail or cauda is a small process extending back from the tip of 
the abdomen, usually rounded or pointed, sometimes sword-shaped. 
Generally, when the honey tubes are wanting, the tail is also absent. 
This is not an ovipositor, but simply a process from the upper arch ot 
the last segment. 
The legs have the usual division, femur (plural femora) the thigh; 
tibia (plural tibiae) the shanks, and tarsus (plural tarsi) the foot. I ne 
tarsus is composed of but two joints, the outer one terminating m two 
slender claws. 
CHARACTERISTICS OF THE FAMILY. 
The species belonging to this family may be distinguished from the 
Psyllidce by their antennae, which never contain more than seven 
joints (the number ranging three to seven), and being without the 
two bristles at the tip. They are distinguished from the Aleurodidce by 
their naked, membranous and usually transparent wings. 
They are small insects, seldom reaching one-fourth of an inch in 
length, and sometimes less than one-twentieth; their bodies are soft, 
and the external integument comparatively tender and delicate, thus 
rendering them very subject to the attacks of predaceous insects and 
parasites. 
The beak is three jointed, varying in length from less than the dis¬ 
tance between two pairs of legs, to more than the length of the body. 
The legs are usually long and slender, the hind pair being sometime^ 
elongated, as though formed for leaping, although none of the special 
appear to posses this power. The head is not so broad as in 
Pst/llidce ; nor is the thorax as greatly developed m proportion to t le 
size of the abdomen. The ocelli or little eyes are sometimes present, 
sometimes wanting, but on this point, on account ot the difficulty of find 
