S TS TBMA TIO ZOOLOGY. 3 



animals, sucli as fishes, birds, or mammals, which have a 

 backbone, are placed together in the branch or sub-kingdom 

 of Vertebrates; those vertebrates, such as the rat, .horse, 

 or cow, which suckle their young, are placed in the cla 

 of Mammals; those mammals which have claws and teeth 

 adapted for seizing and chewing flesh, i.e., are carnivorous, 

 belong to the order of Carnivora. The order of Carnivora 

 is composed of a number of families, such as the cat family, 

 the dog family, etc. A family is composed of a genus, and 

 a genus is made up of species and varieties, the latter being 

 composed of individuals. 



Thus the principle of zoological classification consists in 

 placing animals which are alike by themselves into distinct 

 groups. The following table expresses the zoological posi- 

 tion of the cat: 



Kingdom of Animals; 



Sub-kingdom or Branch, Vertebrata; 

 Okt88, .Mammalia; 

 Order. Carnivora; 

 Family, Felidffl; 

 Genus, Felis; 

 Species, Felis domesticus; 

 Variety. Angorene -: 

 Individual, a single Angora cat. 



The animal kingdom is divided into two series <>f branches: 

 those for the most part composed "f a single cell are repre- 

 sented by a single branch, the Protozoa (animalcules). 

 Those animals whose bodies are formed <>f many cells are 

 called Metazoa.* The series of Metazoa comprises the 

 seven higher branches — i.e., the Porifera, Ceelenterata, 

 Echinodermata, Vermes, Mollusca, Arthropoda, and Ver* 

 tebrata. Their relationships may be expressed by the fob 

 lowing 



* In the latter group the cells are arranged in two, mostly three, 

 fundamental cell-layers. Of these cell layers the outermost is called 

 the ectoderm, the middle the mesoderm, the innermost tixeendoderm, 



