CHAPTER III. 

 CLASSIFICATION OF ANIMALS: GENERAL SURVEY. 



19. Before undertaking any special work on any of the branches 

 of animals, the student should get a general glance at the whole 

 field of animal life, which will enable him to use to best advantage 

 the facts that he has already discovered, more or less incidentally, 

 during his life. The diagram, Fig. i, will aid in bringing the animal 

 kingdom in review. This chapter should be studied in connection 

 with the animals actually brought in by the students in the collec- 

 tions described in the preceding chapter. 



20. Mammals. Man is the highest animal. Similar to him in 

 many ways are the apes and monkeys More unlike him, and yet 

 similar in numerous remarkable particulars, are the horse, the ox 

 the dog, the cat, bears, squirrels, bats, whales, and seals. All of, 

 these bring forth their young alive, after the embryo has been carried 

 for a considerable time and brought to a reasonable maturity in a 

 special organ in the body of the mother. After birth, the mother 

 nourishes the young by means of milk, a special secretion of the 

 mammary glands. This is seen in no other group beside the mam- 

 mals. The skin produces hair or wool, as a partial covering for 

 the body. Man differs somewhat from the other mammals in his 

 structure, but not nearly so much as he and the other mammals 

 differ from all the other animals. 



2 1 . Birds. Another well-developed and numerous group of 

 animals is the class known as birds. There is scarcely another class 

 of animals so easy to distinguish, at sight, as this. They equal 

 or surpass the mammals in specialization, but are very different 

 from them. They are to be recognized by the body covering of 

 feathers, instead of hair; by the modification of the front limbs into 

 wings for the purpose of flying; by their large, shell-covered eggs; 

 and by the fact that the jaw has a casing of horny matter and does 

 not, at least in the case of modern birds, bear teeth. 



22. Reptiles. This class is not nearly so easy to recognize or to 

 define as either of the preceding. This is partly because the animals 



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