8 Flemiptera-ffeteroplera. 
only appears above in the scutellam, which is generally 
largely developed in this order and occasionally to the 
extent of covering the entire abdomen, as in the Scuteller- 
ina; from the sides of the mesothorax extend the anterior 
wings, elytra, or hemelytra, as they are variously styled, 
and from the mesosternum the intermediate pair of legs ; 
the metanotum, as in the Coleoptera, is completely covered 
by the elytra, from its sides extend the posterior wings, 
and from the metasternum the posterior pair of legs; on 
each side of the metasternum is placed the sac from which 
is emitted the odoriferous substance which gives such a 
peculiar smell to so many of the species of this order ; the 
form of the orifice of this sac affords valuable distinctive 
characters for some of the genera; these orifices are situ- 
ated near the posterior coxwe. The thorax has consequently 
five pairs of appendages, the two pairs of wings and the 
three pairs of legs which must now be considered, The 
anterior wings or elytra are almost always coriaceous 
except at the apex which in developed specimens is mem- 
branous; in its most complex form it is composed of five 
divisions, corium, clavyus embolium, cuneus, membrane ; 
these are separated from each other by nerves and are 
generally well defined. In my description of the species 
I have throughout considered the elytra as closed, so that 
the terms anterior, lateral, posterior, etc., refer to them in 
this position; under these circumstances the clavus is the 
narrow strip of the elytra which lies at the side of the 
scutellum, ite sides as a rule are nearly parallel; the corium 
is the whole of the part of the elytra lying outside this, 
bounded at the apex by the membrane ; in the Capside, 
Cimicidee, etc., the externo-apical angle of the corinm is 
separated off and is called the cuneus, the latero-basal 
portion of the corium is also separated off in the Cimicidee 
and is termed the embolium, The membrane is the apical 
portion of the elytra, it is present in nearly all developed 
specimens, its nerves vary very much in arrangement; in the 
