THIRD 
GREAT DIVISION 
OF THE 
ANIMAL KINGDOM, 
(continued.) 
CRUSTACEA, ARACHNTDES, AND INSECTA: 
OR ARTICULATED ANIMALS WITH ARTICULATED FEET*. 
These last three f classes of the Articulata, which were united by 
Linnaeus under the general name of Insecta, are distinguished by at 
least six J articulated feet. Each articulation is tubular, and contains 
the muscles of the succeeding one, which always moves by gyngly- 
mus, that is, in but one direction. 
Tlie first articulation, which attaches the foot to the body, and 
which is composed of two pieces §, is called the coxa, or hip ; the 
following one, which is, usually, nearly in a horizontal ^sition, the 
* Foi- the sake of brevity, I liave designated them by the term Condylopes. This 
series of articulations, of which their body is composed, has been compared by some 
Naturalists to a skeleton, or the vertebral column. But the use of this denomination 
is so much the more fallacious, in as much as these articulations or pretended ver- 
tebra; are mere portions of thickened skin, and as this skin is continuous, simply 
being thinner, and almost membranous at intervals or at the joints, A general 
character, which serves to distingiush these animals from all other Invertebrata, 
consists in their exuviabili/y, or habit of changing their skin. The situation of the 
encephalon, pharynx, and eyes, as in the more elevated animals, establishes the 
limits of the back and abdomen, and of their respective appendages. 
't' Dr. Leach forms a separate class of the Myriapoda. The Arachnides Tra- 
chearim, considered anatomically, might also constitute another, but they arc so 
closely allied to the Pulmonarise in so many other particulars, that we have not 
thought proper to separate them. 
X Hexapoda. Those which have more than six, are termed by Savigny the 
Spiriopoda. I designate them more precisely by the appellation of Hyperhexapoda, 
(more than six feet). 
§ In many of the Crustacea the second portion of the coxa seems to form part 
of the thighs. The tibia, as in the Arachnides, is divided into two joints. 
L 2 
