HETEROPTERA. 4.53 
genera. The fore wings rise wide apart at the base, in order to leave 
space for the large scutellum, which is generally triangular, but some- 
times so greatly enlarged as to cover the whole of the upper side of 
the abdomen, leaving only the lateral margins of the fore wings visible. 
The feet vary considerably in form; in the majority, however, they 
are simple, and formed for walking ; the anterior pair in some is trans- 
formed into a pair of organs of prehension, whilst the hind feet in 
others are greatly dilated and toothed; these limbs are modified in 
the aquatic species, to fit them for their functions. The tarsi are 
short, and never composed of more than three joints. 
The structure of the mouth of these insects indicates at once that 
their nutriment consists solely of the juices of plants or animals, 
which are pumped up the labial canal by the gradual contraction of 
that organ, the substance from which such juices are derived having 
been previously wounded by the four sharp internal sete. By far the 
greater proportion of these animals are found upon plants from which 
they derive their nutriment ; some, however, feed upon other and 
weaker insects, found in similar situations. Such are their habits in 
all their stages, as they continue active, and require food throughout 
their whole existence. The larve are distinguished by the total want 
of any appearance of the rudiments of wings ; whilst, in the pupa, these 
limbs are to be observed upon the back of the meso- and meta-thorax. 
The ocelli are only developed in the imago state. 
The number of species of this order is very great; the majority, 
however, are found in tropical countries, in which they are mostly or- 
namented with a great variety of beautiful colours and markings, often 
vying in splendour with the most splendid of the beetle tribes. The 
aquatic species, on the other hand, are uniformly of an obscure black 
or brown colour. They rarely exceed an inch in length, whilst many are 
not above a line long: they are, for the most part, found in the winged 
state at the end of the summer. Almost every terrestrial species 
in the order emits, on being suddenly alarmed or touched, a peculiar 
odour, more or less disgusting, and which is so well known in the 
common bed-bug ; but which, in some few species (as in Lygeeus Pas- 
tinacie), assumes a more grateful scent, probably resulting from the . 
nature of the plant on the juices of which it subsists. Others emit 
the odour of acetic ether, or exhalations similar to that of the majority 
of the Carabide. Fruit, such as raspberries, &c., is occasionally ren- 
dered very offensive to the taste by some of the garden species having 
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