270 
SYSTEMATIC ARRANGEMENT. 
Figures 2-5 illustrate the structure of one of the homoptera, 
Cicada atrata , a native of China. — Fig. 2. The head seen in 
front ; a, a, the eyes ; 6 , the three ocelli ; c , c, the antennse ; 
d , the clypeus ; e, the labriun ;/, the labium, forming a sheath 
for the reception of < 7 , < 7 , the hair-like mandibles, and A, A, the 
hair-like maxilla;. — Fig. 3. Part of the mouth ; rf, the clypeus ; 
c, the labrum ; f'f"f"* tho two basal, and part of the long 
terminal joint of the labium Fig. 4. The seven-jointed an- 
tennae Fig. 5. Underside of the thorax and abdomen ; T 1, 
prothorax \ T 2, mesothorax ; T 3, metathorax ; A, abdomen. 
We have already mentioned the comparative ex- 
tent of the different orders, from which it appears 
that the one now under consideration is the fourth 
in the scale, nearly 25,000 species being supposed to 
exist. Rather more than 600 different kinds have 
been found in Britain ; but most of these are incon- 
spicuous insects of small size and obscure colouring. 
The metamorphoses of these insects may he de- 
scribed as merely a series of moul tings. The larvae 
and pup© are alike active, the latter distinguishable 
from the former only by having two small projections 
on the back which conceal the wings and wing- covers. 
The only perceptible difference in apterous species 
in their various stages, is that arising from size. 
In proceeding to illustrate this order by a selection 
of a few species from the numerous tribes it contains, 
we shall first advert to that section which has been 
named, 
Heteroptera, 
The distinguishing marks of which it may be of ad- 
vantage briefly to recapitulate in this place. The 
