STRUCTURE OF INSECTS. 



65 



Fig. 48, and may stand as a type of all the other Beetles, 

 Fig. 48. since they do not differ in 



their structures. This spe- 

 cimen is of the natural 

 size, but the sections are 

 somewhat magnified, that 

 the smaller parts may be 

 more distinctly seen. 



The head c, Fig. 49, 

 "contains the principal en- 

 largement of the nervous 

 system, or the brain, the 

 scull or cranium being us- 

 ually the hardest part of 

 the insect. To the head 

 are attached the antennae, 

 and instruments of masti- 

 cation. The latter are much more complicated in Insects 

 than in larger animals. Those which divide their food, 

 have a double set of jaws, called mandibles and maxilla, 

 besides which, there are four other moveable pieces 

 called palpi, and labial palpi. The mandibles or upper 

 jaws, m, cut the food ; the lower, or proper jaws, j, 

 masticate it; the palpi, p, and the labial palpi, /, appear 

 to be instruments of sense by which the insect judges of 

 the quality of its food. The motions of all these parts 

 are horizontal, and not vertical as with us, and other an- 

 imals having incumbent maxilla?. To obtain an idea of 

 the motions and uses of these parts, it is only necessary 

 to watch an insect for a few moments while feeding. 

 Fig. 49. 



The trunk, or thorax is composed of three parts, con- 



What are the jaws of insects ca-led ? What other pieces belong to the 

 mouths of insects 1 What are the uses of the mandibles and proper 

 jaws 7 What are the uses of the palpi 1 



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