248 CLASS VIII. 
which Cuvier, as stated above (p. 33), divided the entire Animal 
Kingdom. We allude to the Type of Articulate Animals, which 
may be separated into two divisions. The first division includes 
articulate animals without jointed feet (apoda, the Annulata), the 
other articulate animals with feet (Condylopoda). Again, articulate 
animals with limbs (Insects of Linn.mus) are divided into three 
classes, of which the first, immediately to be treated of, retaims the 
name of Jnsects; the two other classes, those of the Avachnids and 
of the Crustaceans, comprehend those animals which Linn.aius con- 
sidered as wingless Insects. 
Insects (in the narrower meaning of modern systematic Zoology) 
are mostly provided with wings; but the presence of these organs 
of motion does not constitute the character of the class, That is to 
be sought for in the head distinct from the trunk, to which two 
antenn are attached, and in the Respiration by means of air-canals 
distributed internally through the body and generally divided into 
very fine branches. The first of these characters distinguishes the 
Insects from the Arachnids in which the head and thorax form a 
single piece, and which have no antenne, the other distinguishes 
them from the Crustaceans, whose respiratory organs are gills or 
other external appendages. 
The names Jnsecta, notched animals, and in Greek évroya, have 
all the same meaning. From the last is derived the word Entomo- 
logy (Insect-Science). 
The species belonging to this class are very numerous: in this 
respect no other class can be compared with Insects. In treating 
therefore of this class we must keep within strict limits, that we may 
not too greatly extend our work in the estimation of those who take 
less interest in this special part. 
We will first describe the external structure of these creatures a 
little more precisely The body of the six-footed Insects, which 
make up by far the largest portion of this class, is separated into 
three parts: head, trunk, and abdomen. On the head, besides the 
parts about the mouth, the antenne and eyes are distinguished. 
By Antenne are understood moveable jointed threads, which, 
unconnected with the oral organs, are attached to the head, usually 
close to the eyes. The number of joints is very different; in But- 
terflies, for instance, very large, in Beetles, mostly eleven, &c. All 
insects in the perfect condition or last period of life have two 
A Yes 
