CHAPTER III 

 SOME COMMON ANIMALS CATS AND DOGS 



HAVING now traced the main outlines of the structure of the 

 animals which make up the class Mammalia, an attempt may be 

 made to indicate the different types of mammals which have 

 come into being. From the evidence afforded, on the one hand 

 by fossils, and on the other by the study of the early stages of 

 development, and of the anatomy of the adult stages of these 

 various types, we learn that they have arisen by a process of 

 slow and orderly growth from ancestors of more simple character. 

 Thus the ancestors of the deer had no antlers ; the ancestors of 

 the elephants were quite small creatures resembling the " dassies " 

 of South Africa the " coney " of the Bible; the ancestors of 

 the horses were little bigger than a good-sized dog, and possessed 

 five toes on each foot. Further, creatures now so unlike as horses 

 and hoofed animals generally, on the one hand, and the carniv- 

 orous types, such as bears and lions on the other, can be traced 

 to a common ancestral type. Evidence in support of this can be 

 found in the more advanced scientific text-books, or in, say, the 

 British Museum. The purpose of these chapters is to show the 

 uniformity of plan which may .be traced in the framework of the 

 most unlike types ; and to indicate the ends which have been 

 gained, so to speak, by the departures from the common ancestral 

 type, now in one direction, now in another. 



No better beginning could probably be made than by comparing 

 such familiar animals as the cat and the dog. 



Cats and Dogs Contrasted. These two animals, it should be 

 noted, have for countless generations been the constant com- 

 panions of man. In the course of time, man, by careful breeding, 

 has done much to change the external form and increase the 

 docility and usefulness of the dog, but has succeeded in effecting 

 but little change in the cat. And this because the dog, like man, 



