INTRODUCTION. 3 



MAMMALIA (vertebrates suckling their young). 



Prototheria: Oviparous mammals. Ornithorhynchus. 

 or duck-bill and Echidna or spiny 

 ant-eater. 



Eutheria: Viviparous mammals with anus and 

 urogenital opening distinct. 



Marsupialia (opossums and kangaroos). 



Insectivora (moles, shrews, and hedge- 

 hogs). 



Edentata (sloths and ant-eaters). 



Chiroptera (bats and flying foxes). 



Rodentia (rabbits, squirrels, mice, and 

 rats). 



Cetacea (whales, porpoises, and dol- 

 phins). 



Sirenia (sea cow). 



Ungulata (the hoofed mammals). 



Carnivora (dogs, cats, wolves, and 

 foxes). 



Primates (monkeys and man). 



A glance at the above outline shows that the class Mam- 

 malia is divided into two subclasses, the latter of which 

 includes ten orders. Each of these orders consists of 

 several families which in turn are composed of genera made 

 up of species. The order Carnivora includes eleven fami- 

 lies, of which Canidae (the dogs), Felidae (the cats), and 

 Ursidse (the bears) are the most frequently seen in America. 

 The family Felidae is represented by only two living genera, 

 Cyncelurus and Felis. The genus Felis includes several 

 species, of which Felis leo (the lion), Felis tigris (the 

 tiger), and Felis domestica (the cat) are the most familiar. 

 Of the last species, there are several varieties, such as 

 Maltese, Angora, and Manx cats. 



Linnaeus, born in Sweden, 1702, invented the system of 

 binomial nomenclature in accordance with which the scien- 

 tific name of every plant and animal is composed of two 

 parts, the generic and specific. Thus the house cat is 

 designated Felis domestica; the lion, Felis leo; the dog, 



