THE DOG. 
CHAPTER I. 
THE DOG AND ITS HABITS, 
Origin—Characteristics---Age, &c,, &c. 
HE DOG belongs to the division Vertebrata, and 
the class Mammalia. It is also in the order Fera, 
the family Fé/ide, and the sub-family Canina, which in- 
cludes the dog, wolf, jackal, and fox. This sub-family is 
distinguished by having two tubercular teeth behind its 
canine teeth in the upper jaw; and the Canis familiaris 
has the pupils of the eye round, while in the fox they are 
like those of the cat, perpendicular slits, and in the wolf 
oblique ones. Volumes have been written on the origin 
of the dog, but our knowledge on this subject may easily 
be summed up in one little word, z/; I shall therefore 
not inflict upon the readers of this book all the various 
arguments vo and con; suffice it to say, that the dog is now 
an inhabitant chiefly of cold and temperate climates; that 
it rapidly degenerates if transported to a very warm one, 
as is seen in India and China, but that it will bear every 
climate from the Arctic circle to the Equator without loss 
of life. The dog is a carnivorous animal by nature, 
though he will feed upon and devour any vegetable sub- 
stance that comes in his way if pressed by hunger. In 
his domesticated state he thrives best upon a mixed diet, 
and is usually considered, and with truth, as omnivorous. 
.His teeth are fitted for tearing flesh, and he has no true 
grinders suited to bruise grain; his stomach is a simple 
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