230 FIRST LESSONS IN ZOOLOGY. 



excepted, is a gibbon, which can sing "a complete and 

 correct octave of musical notes." 



While the cat gives out no disagreeable odors, there are 

 others of its class which are mutually attracted or are indi- 

 vidually protected from the attacks of other species by odors. 

 The scent-bags or odoriferous glands, secreting a fluid 

 differing in consistency in different animals, are situated 

 near the base of the tail, as in the skunk, pole-cat, musk- 

 deer, civet-cat, and allies, or they may be developed in the 

 side of the face, as in the male elephant, as well as in sheep 

 and goats. The odor is either of musk or some form of it. 

 The sense of smell must be very delicate, a Tj.FoV.wo- P ar ^ 

 of musk being perceptible, says Mivart, when mixed with 

 common air. The shrew-mice, by reason of their odorifer- 

 ous glands, are disliked and consequently not hunted by 

 birds. Universal deference is paid to the skunk; few dogs, 

 and only those which are either inexperienced or peculiarly 

 gifted, attacking them. 



The cat renews her fur by shedding the hair gradually, 

 the color remaining the same throughout the year. But 

 there are a few mammals which have a summer and a win- 

 ter dress. The American hare, ermine, least weasel, and 

 long-tailed weasel, soon after the fall of snow in the begin- 

 ning of winter, assume their winter dress, the ends of the 

 hairs first turning white. 



SUB-CLASSES OF MAMMALS. 



1. With long toothless jaws like a bird's 



bill OrnitJiodelpMa. Duck-bill. 



2. With a pouch for holding the young. .Mnrsupialia. Opossum. 



3. With a placenta; brain in most cases 



with convolutions MonodelpMa. Rat, Cat, etc. 



