84 NATURAL niSTORY. 



produced by their agency. Many feed upon putrid ani- 

 mal or vegetable matters, which might otherwise become 

 dangerous or fatal ; others are made use of in medicine 

 and the arts ; a few furnish food for man, and some give 

 pleasure to the observer by their brilliant colors. They 

 also serve as nourishment for many species of animals, 

 birds, and fishes ; and a few of the races, which furnish 

 honey, wax, and silk to man, add much to his comfort 

 and are greatly prized. 



Insects are divided into three large divisions, namely : 



I. Crustacea^ to whichj)elong Crabs, Lobsters, Sea- 

 lice, etc. 



II. ArachnidcB, or Spinners, as Spiders, Mites, etc. 



III. True Insects, such as Centipedes, Flies, Crick- 

 ets, Grasshoppers, Butterflies, Ants, Bees, etc. 



FIRST DIVISION. 

 CRUSTACEA. 



The Crustacea Class comprises all of the race that 

 breathe through branchiae that lie concealed under the 

 borders of their shells. They have no wings ; the eyes, 

 of which most of them have two, of a very complicated 

 structure, are composed of a number of small facets 

 covered with one cornea ; the head is provided with four 

 antennae or feelers ; the mouth is furnished with three 

 pair of jaws, and behind these are the palpi, which are 

 small articulated filaments, and are employed by the 



