STRUCTURE OF INSECTS AND ARACHNIDA. 105 
which was interrupted at a very early period. In some 
I however, the general form is the same from the first, 
“and the wings are the only parts deficient ; these gradually 
ee a 
Ne 
ae 
/ Srd pair of Legs --—-—---~~ 
ir? 
, 
+ 
= 
q 
: Tibia 
P 
‘ 
q 
; oe aaees 
: Fig. 46.—SEELETON oF an IxsEct. 
make their appearance, and the insect is then complete. Such 
is the case with the Grasshopper and Cricket; and a change 
_ of this kind is termed an incomplete : 
_ 98. The animals of the class Aracunipa, which includes 
- the spiders, scorpions, and mites, are, like Insects, articulated, 
_ breathing air, and possessing legs, but the number of these 
3 
_ legs is never less than eight; there is an entire absence of 
__ Wings, and the head is united with the thorax, so that the 
body seems to be formed of two principal divisions,—the 
__ cephalo-thorax (as it is termed), and the abdomen. In fig. 46 
we have a representation of the arrangement of the parts con- 
=F 
