LINNZAN SYSTEM. — INSECTS. Loe 
struments of sensation. They are destitute of external 
nostrils and ears, though some of them evidently enjoy 
the senses of hearing and smell. 1. The eyes are 
usually two, sometimes more, without eyelids, and rarely 
placed on a movable peduncle. 2. The antenne are 
two, placed on the head, usually before the eyes: they 
are composed of an indefinite number of articulations, 
and convey an unknown sensation, probably that of 
the touch. 3. The -feelers are sensorial, movable, 
affixed to the mouth, generally four, sometimes two or 
six; and consist of two, four, or six joints. 4. The 
mouth is generally placed beneath the head, sometimes 
in the breast, and in a few is wanting: the jaws are 
transverse, and movable laterally. 5. The stemmata 
are three shining spots placed on the crown. 6. The 
trunk is placed between the head and abdomen, sup- 
ported by the feet, with the thorax above; behind which 
is the seutel, or escutcheon, and the sternum and 
breast beneath. 7. The abdomen is usually annulate, 
with five segments; perforated at the sides with five 
spiracles, or breathing holes, with the back above and 
the belly beneath ; and is terminated by the tail, which is 
sometimes armed with a sting. 8. The wings are 0, or 
two or four: the upper ones are often crustaceous shells, 
covering the lower ; sometimes semi-crustaceous wing- 
cases, or of a substance between the membranaceous wings 
and crustaceous shells. 9. The /egs consist of three 
distinct divisions, viz. the thighs, shanks, and tarsi, 
which are articulated, and terminated by nails: some 
have a hand, or chelate kind of claw, with a movable 
thumb. 10. The poisers are composed of a head, af- 
fixed to a small pedicle, and placed under the wings of 
the dipterous order, or such as have but two wings. So 
far for the parts of insects. 
(211.) The changes, or metamorphoses, of what 
Linneus considered insects, are thus spoken of :—Most 
of them undergo a triple metamorphosis or transform- 
ation, effected by casting off the different coats or cover- 
ings in which the perfect insect is inveloped. The egg 
