STRUCTURE OP INSECTS AND ARACHNID A. 
10 5 
life, which, was interrupted at a very early period. In some 
tribes, however, the general form is the same from the first, 
and the wings are the only parts deficient; these gradually 
Antennas 
Eyes 
1st pair of Legs 
1st pair of Wings 
2nd pair of Legs 
2nd pair of Wings 
3rd pair of Legs 
Tibia 
Tarsus 
Fig. 45.— Skeleton of an Insect. 
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 metamorphosis. 
98. The animals of the class Arachnid a, which includes 
the spiders , scorpions , and mites , are, like Insects, articulated, 
breathing air, and possessing legs, but the number of these 
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- 
