EXPLANATION OF THE CHART OF THE ORDERS OF 



MAMMALS 



To the student of Natural History, the Order is the master-key to class- 

 ification; and these grand divisions should always be kept fresh in the 

 mind. 



This chart is based on the well-known fact that in the pursuit of a 

 difficult study, any scheme which properly and truthfully appeals to the 

 eye is an aid both to the understanding and the memory. It shows the 

 relative importance of the various Orders of Mammals, but not their 

 relative sizes, based on the number of species in each, as has been done 

 later on with the birds. If number of species were given precedence over 

 economic importance, the Order Glires would dominate, and the Order 

 Ungulata would appear small and insignificant. 



It is impossible to construct a diagram which will show correctly the 

 relations which the various Orders bear toward each other, anatomically. 

 This is because some Orders are characterized by their teeth, some by 

 their feet, or hands; others by their wings, and two by their mode of pro- 

 ducing their young. 



It will be noted that: 



The Primates, of the tree-tops, have the highest position. 



The Cete, which in some respects are the lowest of the Mammalia, 

 occupy the lowest position. 



The Bats are shown in mid air, and the Insectivores appear under- 

 ground, where they live out their lives. 



The Seals and Sea-Lions appear both on the shore and in the sea, and 

 the Sirenians are located in an estuary. 



The Ferae, Glires, and Ungulata spread throughout the whole visible 

 earth, covering forest and plain, sea, pond, and stream, from the sea to 

 the most distant mountains. 



The Monotremates, or egg-laying mammals, are quite apart from all 

 other land mammals, and appear low down, near the home of the ducks, 

 as shown on the bird chart. The space allotted to this strange Order 

 has been made egg-shaped, to suggest the leading characteristic of its 

 members. 



