MAMMALS OF MINNESOTA. 13 



CHAPTER I. 



The first question which we encounter is "What is a mam- 

 mal?" Every one is practically familiar with a greater or less 

 number of mammals, and is possessed of a more or less dis- 

 tinct notion of the points of similarity and diversity between 

 such of these animals as are most familiar, but it may be sus- 

 pected that such of my readers as are not themselves natural- 

 ists may not be prepared to state the distinctions which sepa- 

 rate mammals from all other animals. It is remarkable how 

 few ideas are united in the popular conception represented for 

 example by the words cow, dog, cat, etc. We may perhaps think 

 of a cow as an ungainly quadruped with hoofs and horns, which 

 occupies herself in chewing a cud and brewing milk. One 

 familiar with country life will be likely to add that the hoofs 

 of a cow are divided and the horns are furnished with a core 

 of bone and not, like those of an elk, solid and deciduous and, 

 perhaps, that there are certain peculiarities in the dentition. 

 A keen observer would recall that there are really four hoofs 

 which represent four toes on each foot, that the stomach is 

 curiously differentiated and thus exhaust what are popularly 

 considered the distinctive features of a bovine. So able a 

 writer as John Fiske speaks of a "hoof as made up of five 

 claws grown together and furnished with a nail in common. " 

 (The Destiny of Man, p. 36). Yet few would ever have thought 

 to inquire which of all these points does a cow have in common 

 with a mouse, a kangaroo or an elephant, which animals are as 

 truly mammals as the cow or her master. 



The mammals are members of the sub-kingdom Vertebrata 

 among the prominent characters of which are the following: 

 The body is composed of two cavities of unequal size, the 

 uppermost of which contains the central part of the nervous 

 system, or, in other words the brain and spinal cord, while the 

 lower cavity contains the viscera. The nervous cavity is separ- 

 ated from the visceral by a chain of bones which usually also 

 sends up bony walls which completely enclose the organs 

 contained in it. The anterior portion of the nervous system or 

 brain is usually highly developed and encased in a complicated 



