The Elements of Entomology

Description

ELEMENTS OF ENTOMOLOGY.



THIRD BRANCH OF THE ANIMAL KINGDOM,



ARTICULATED ANIMALS.



LESSON I.



GENERAL CONSIDERATIONS. Structure of Articulated Animals Division of the Third Branch of the Animal Kingdom.

CLASS OF INSECTS. Organization Metamorphosis Classi- fication.



1. The third great division, or Third Branch of the Animal Kingdom, includes all animals that are constructed on the same’ general plan as insects. Their internal structure is essentially different from that of animals belonging to any of the other three branches of the animal kingdom ; and their external characters are so decided and evident that it is almost always easy to recognise them at first sight.

2. They are termed articulated animals animalia articulata because their body is divided into sections, and seems to be composed of rings, placed in a contiguous series on a line with each other (Jig. 1). The extremities in many instances are also formed in this manner. These rings are formed of portions of

1. What description of animals are comprised in the third branch of the animal kingdom ?

2. Why are they termed articulated animals ? How are the rings formed? Have articulated animals any skeleton ?

skin which are harder and thicker than the rest of the body. In some cases this annular arrangement arises so’ely from the existence of a certain number of transverse folds or plaits which groove the skin and encircle the body ; but in most instances the animal is enclosed in a species of solid armour, composed of a series of rings united to each other in such a manner as to permit of motion.
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