44 



Introduction 



First and largest of all the categories is that to which all animals 

 belong: the Animal Kingdom. The Plant Kingdom, on the other 

 hand, contains all the plants. In general, there is little or no difficulty 

 in distinguishing between these two main groupings. 



The next step in the classification of any animal is to determine 

 whether that animal consists of but a single cell or of many cells. Those 

 consisting of but a single cell are classed in the subkingdom Protozoa; 

 those with many are in the subkingdom Metasoa. 



Each of these subkingdoms is in turn divided into phyla (sing. 

 = phylum). In general, the members of the various phyla are recog- 

 nizable without much difficulty. Within each phylum there are further 

 categories, each of which becomes more restricted in its definition. For 

 example, consider man. He is a member of the phylum Chordata, sub- 

 phylum Vertebrata, due in part to the possession of a spinal column. 

 His body is covered with hair, and this characteristic (along with 

 others) places him in the class Mammalia. Here he has the company 

 of many other familiar forms : the dogs, cats, cattle, rodents, and 

 many others. Within the class Mammalia are many different orders, 

 and man's order is known as the Primates, whose members also include 

 the lemurs, monkeys, and apes. In general, they can all be characterized 

 by the fact that the limbs are elongate and terminate in five digits 

 having nails, not claws. Within this order are many famHies. Man is 

 in the family Hominidae, a family which has but a single living genus and 

 species, man himself, scientifically known as Homo sapiens Linnaeus. 



For the sake of clarity, a chart showing the classification of man 

 as well as two other forms is shown here. 



The complete scientific name of each of these is thus : Rattus nor- 

 vegicus Linnaeus, Homo sapiens Linnaeus, and Romalea microptera 

 Beauv. By careful observation of this entire classification, it can be 

 noted that the separation between man and the rat occurs at the order 



