70 FIRST BOOK OF ZOOLOGY. 



It will be advisable, also, for the pupils to utilize the 

 broken specimens of insects by selecting the wings of dif- 

 ferent insects and gluing them upon a card, labeling each 

 one. Different kinds of antennae might be fastened upon 

 another card, and the legs of some widely-different insects 

 may be arranged in the same way. For example, let them 

 take the hind-pair of legs of a grasshopper and of a water- 

 beetle. It will be instructive to observe how different these 

 two kinds are, and how admirably one is adapted for jump- 

 ing, while the other is so perfectly fitted for a paddle. By 

 making comparative collections of this kind the pupils will 

 learn a great deal regarding the structure of insects. 



68. The pupils have thus far learned that a true insect 

 has the body divided into regions called the head, thorax, and 

 abdomen ; that the head bears the mouth-parts, antennae, and 

 eyes. The thorax has the legs and wings, while the abdomen 

 has only the caudal or tail appendages, and these are not 

 often apparent, They have also learned that the thorax is 

 made up of three segments, not often plainly marked, while 

 the abdomen is composed of a greater number of segments, 

 in most cases very plainly apparent. As each segment of 

 the thorax is characterized by having attached to it a pair of 

 appendages, and as the head contains a number of append- 

 ages, it is believed by many naturalists that an insect's head 

 is composed of a number of segments, so closely merged 

 together, however, as not to be distinguished, except theo- 

 retically. As naturalists, however, differ in their estimate of 

 the number, we will leave this difficult problem for more 

 advanced students to study. 



