430 CLASS VIII. 
The disagreeable smell, peculiar to most heteroptera, seems for their 
protection, and is caused by a fluid that escapes through two aper- 
tures, one on each side, beneath the thorax at the insertion of the 
third pair of feet. According to Lkon Durour this fluid is 
secreted by a small round or oval pouch, commonly of a yellow 
colour, which is situated in the abdomen; it is rarely double. 
Many genera of henviptera are met with only in warm countries, 
and the European species form but a small part of the numerous 
order. 
Section L. Homoptera. Hlytra deflected, in most coriaceous or 
membranous, similar to posterior wings, but larger and stronger. 
Rostrum rising from the inferior part of head, inflected beneath the 
breast between the bases of the feet. Thorax gibbous, with first 
segment shorter. 
In this division, which as well as the second, WEstwoop ranks as 
a distinct order, the upper wings are constantly of a similar substance, 
and not half-horny or leathery and half-membranous. The antennz 
consist in many of more than six joints. The beak lies on the 
breast (rostrum pectorale). All live on juice of plants. The females 
often have an instrument for laying their eggs, composed of three 
filaments, toothed plates or saws, enclosed between two valves. 
A. Metamorphosis (in males at least) complete. 
Family XX XV. Coceina (Gallinsecta REAuM.) Males winged, 
with mostly two wings, without rostrum. Wings without cells, 
with only two longitudinal nervures. Antenne mostly with nine 
to eleven joints. 
Females (one genus excepted) apterous, attaching themselves to 
trees or herbs at the time of parturition, sometimes assuming the 
form of a gall, their own vesicular dead bodies covering their eges. 
Gall-insects. These insects were thus named by Réaumur from a 
superficial resemblance of the pregnant female to a gall-nut. (See 
above, p. 384). The joints of the tarsus have not been given by 
us amongst the characters on account of the minuteness of the 
objects and the prevalent uncertainty ; for whilst many writers (ea. 
gr. LATREILLE and WeEstwoop) ascribe one joint alone to this family, 
and distinguish it principally by this, others assign three (BoucHE 
