HOMOPTERA. — PSYLLIDM. 435 
two joints in the tarsi, with antenne longer than the head, and com- 
posed of from six to ten filiform joints ; whilst they differ from the 
Monomera by the winged individuals possessing tour wings, the an- 
terior being ordinarily of the same membranous texture as the pos- 
terior. The section consists of the families Psyllide, Aphide, and 
Aleyrodidz; the genus Aleyrodes disagreeing so much from the 
Aphidz, in which it is placed by Latreille, and from the Coccide, in 
which Burmeister arranges it, that I have thought it most natural 
to consider it as forming a distinct family. 
Fig. 117. 

The family PsyLL1p& has long or moderately long filiform antenne 
composed of ten joints, the basal one being thick, and terminated by 
two short sete (jig. 117.1. Psylla —?, the largest British species) ; in 
Livia they are much shorter, with the second joint very greatly di- 
lated ; they are inserted in front of the eyes, at the sides of the head, 
which part of the body is deeply cleft in front; the eyes are lateral 
and prominent, the ocelli, three in number, placed in a triangle, the 
posterior ones close to the eyes (fig. 117. 2. head above); the pro- 
muscis is short, triarticulate, arising almost between the fore legs 
(jig. 117. 3. head beneath), enclosing several very slender elongated 
sete, capable of being thrust out to a great length, as in fig. 117. 6.; 
the thorax is of a very large size, the prothoracic collar is very short, 
the mesothorax and metathorax fully developed, the former composed 
of several parts (fig. 117. 1.), terminated by a small scutellum. Be- 
neath, the epimera of the metathorax are singularly produced behind 
the place of insertion of the hind legs (which are pushed forwards), 
and terminated by two strong spurs (fig. 117.5. body sideways); the 
tarsi are composed of two joints (jig. 117. 4. hind leg); the wings, 
which occur in both sexes, are deflexed at the sides of the body, the fore 
FFQ2 
