CLASSIFICATION. 1 3 



flakes. As a general rule, the coat falls off in spring or autumn and is 

 replaced by new hair. 



In one very striking point, the voice, the Mammalia are far inferior to 

 the birds. Man, indeed, possesses a voice that can produce articulate and 

 melodious sounds, but his fellow mammals are a tuneless and songless 

 race, and their tones have no charm for us. The voice of most of them 

 is disagreeable, and becomes more so when the animal is e.xcited. Love, 

 whicli bids the bird warble its melodious lays, only makes the voice of 

 the mammal more unpleasing. Compare the notes of our feathered 

 denizens of the air and the amatory serenades of the domestic cat. We 

 admire indeed tlic poet's verse that tells us how 



" The lowing;; herd winds slowly o'er the lea," 



kut we admire it as a picture of evening; it is not the "lowing," but the 

 idea of return from labor that please us. "Lowing" in itself is as inhar- 

 monious as the bleating of sheep, the grunting of swine, the braying of 

 the ass. The voice of all mammals, excepting man, is rough, dissonant, 

 devoid of flexibility, and not susceptible of cultivation. 



We must now proceed to enumerate tiie orders into which all the 

 animals comprehended in the class MAMMALIA are divided. Without 

 such a further classification we should be in a labyrinth " in endless 

 mazes lost." We will, however, first give as briefly as possible a defini- 

 tion of the class. 



" The Mammalia form a class of Vertebrate animals. They bring 

 forth their young alive and nourish them with milk. They breathe by 

 means of lungs; their heart is four-chambered; the appendages to the 

 skin take the form of hair." 



The basis of classification of the Mammalia has been a subject of 

 frequent discussion. The first and most obvious division is into Pla- 

 cental and Non'-Pi.acental Mammals; in the former the unborn 

 young are nourished by means of the placenta, and are not born till 

 they are able to obtain their natural food, milk, by their own exertions. 

 In the latter, the young are born before there is any necessity for a pla- 

 centa to supply them with the nutrient materials of the mother's blood ; 

 they are born so helpless that they cannot suck, but the milk is forced 

 into their mouths by a muscle surrounding the mammary gland. But 

 these grand divisions are too large, for the class of placental mammals 

 embraces animals so diverse as man and whales, bats and elephants, 



