47 
Subkingdom Articulata. Jointed Animals. 
In these animals, the symmetrical body is 
divided into 
which are jointed together. 
a series of rings called segments, 
but its place is supplied by the skin, which is usually | 
hard, and often covers the internal organs like a 
coat of mail, and serves as a support for the attach- 
ment of powerful muscles. The nervous system 
There is no skeleton, | 

consists of two cords, which run along the under- 
surface of the body, and are connected by knots 
called ganglia. Above the mouth are two large 
ganglia with which the cords commence, and which 
form a kind of brain. Creatures of very different 
form and habits are included in the Articulata, 
Class Insecta. 
Invertebrate animals, with the body composed 
of three different divisions, the head, thorax, and 
abdomen. The head is provided with eyes, antenna, 
and mouth-organs adapted either for biting or for 
sucking; and the thorax bears the organs of loco- 
oS 
motion, which consist of three pairs of jointed leg 
and in most cases, of two pairs of wings. 
Insects do not breathe by means of lungs or 
’ 
gills, but by tracheze, or air-tubes, which open on 
the sides of the body. Insects lay eggs, but pass 
through four stages of existence in which they differ 
more or less in appearance and habits; namely, the 
the larva or caterpillar, the pupa or chrysalis, 
and the imago or perfect insect. 
CSS 

Insects are extremely numerous, both in species 
and individuals; and they are found everywhere on 
land and in fresh water , though very few true in- 
sects inhabit the sea, where their place is filled by 
the Crustacea. 
at present, 
260,000 species of insects are known 
and thousands more remain to be dis- 
covered, while in England we have about 12,000 
species. They feed on all kinds of animal and vege- 
table substances, and there is no plant which is not 
liable to the attacks of various species; and none 
more so than the oak, which provides food for 
several hundred different species of insects, many of 
which are never found on any other plant. 
Insects are divided into seven principal Orders, as follows: 
a) Insects with perfect metamorphoses: 
1. Coleoptera (Beetles). 
2. Hymenoptera (Bees and Wasps). 
3. Lepidoptera (Butterflies and Moths). 
4. Diptera (Two-winged Flies). 
5. Neuroptera (Dragonflies &c.). 
b) Insects with imperfect metamorphoses: 
6. Orthoptera (Grasshoppers and Crickets). 
7. Hemiptera (Bugs). 
Of these, Orders 1, 2, 5 and 6 have biting 
jaws in the perfect state, and are called /vsecta 
Mandibulata; and Orders 3, 4 and 7 have mouth- 
Order I. 
Coleoptera. 
organs adapted for suction in the perfect state, and 
are called Jnsecta Hanstellata, 
(Beetles). 
Plate XXIV (left side). 
These are mandibulate insects with perfect me- 
tamorphoses. The organs of the mouth consist 
chiefly of the upper and lower jaws, (mandibles and | 
maxilla) an upper and lower lip (labrum and labium) 
and the chin (mentum). The maxilla are provided 
with one or two pairs of jointed organs, called maxil- 
lary palpi, and the labium with one pair, called labial 
palpi. The antenne differ in length in different 
species, but usually consist of 11 joints. The front 
wings are called elytra, or wing-cases, and are hard 
and horny, and the hind wings, which are the true 
organs of flight, and which are generally colourless 
Amphibia. 

and transparent, are folded beneath them. The 
larvae are usually worm-like, with six legs, and 
a horny head. The pupa is motionless, but 
exhibits the oufline of the perfect insect. The 
accompanying figure represents the principal parts 
of the body of a cockchafer. a. Head with antennz z 
and projecting maxillary palpi. 6. Prothorax, and 
first pair of legs. c. Mesothorax, with the middle 
legs, and elytra %. d. Metathorax, with the hind 
legs and wings e. g. shows how the wings are 
folded when not in use. f. Abdomen, consisting of 
9 segments. This structure is common to all 
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