12 



DIVISIONS OF ARTICULATA. 



circulatory apparatus is less complete, and in some cases is alto- 

 gether absent. 



10. In a word, we see that articulated animals are chiefly dis- 

 tinguished from the other three branches of the animal kingdom 

 by the arrangement of the nervous system and by the body being 

 surrounded by a series of rings which seem to divide it into so 

 many transverse segments. 



11. This great branch of the animal kingdom is composed of 

 six distinct classes of animals ; namely, insects, my'riapods, 

 arach'nidans, crusta'ceans, cirr'hopods, and anne'lidans. The 

 following table exhibits some of the characters by which they 

 are distinguished from* each other. 



A distinct head,' 

 thorax and abdomen ; 

 three pairs of legs, and 

 generally provided with 

 wings. Tracheae : but 

 no circulatory appara- 



CLASSES. 



INSE'CTA. 



10. How are articulated animals distinguished from the other three 

 Branches of the animal kingdom ? 



11. Into what classes is the Branch of articulated animals divided ? 



