THE COMMON DOG. 85 



a perfectly dark night, would leave the room by the 

 door, and, going round the corner of the house to 

 the spot, would never fail to return with the same 

 stone in his mouth. 



To account for this peculiar nicety of scent, it is 

 to be remarked, that, in the Dog, the cavity of the 

 ethmoid, or spungy bone, at the top of the nose, 

 betwixt the nose and the brain, has a larger surface 

 than that of most other quadrupeds. The olfactory 

 nerves pierce this bone, and are extended over it; 

 and their extent of surface is, consequently, greater 

 than in other animals. 



The females have commonly two births in the year; 

 and they produce, at each litter, from four to twelve 

 young ones. These come into the world perfectly 

 blind,, their eye-lids not only being closed together, 

 but adhering by a membrane, which breaks away as 

 soon as the muscles of the upper eye-lid acquire suf- 

 ficient strength to raise it, and overcome this ob- 

 stacle. In most Dogs, the eyes are opened about 

 the tenth or twelfth day. When first produced, the 

 bones of the skull are not finished; the body is 

 very thick, in proportion to its length; and the 

 whole form is incomplete. But, in the course of 

 two months, the animals begin to attain their shape 

 and strength, and learn to use all their senses. 

 Their growth, during this period, is very rapid. 



In about two years, Dogs arrive at a state of ma- 

 turity; and the usual term of their lives is from ten 

 to fourteen years* Some Dogs, have, however, 



G 3 attained 



