CLASSIFICATION 13 



THE CLASSIFICATION OF ANIMALS 



At the present time there are about 523,000 species of 

 animals known, with perhaps an equal number yet to be 

 described. It goes without saying that such a number of 

 distinct kinds requires some means of classification, if only 

 for convenience in cataloguing. There are in general two 

 systems of classification natural and artificial. The first 

 is the result of an attempt to show genetic, or blood, rela- 

 tionships; the second term is applied to any system of 

 grouping which will enable one to bring animals together 

 which show certain points of similarity, whether such 

 characteristics are of fundamental importance or not. la 

 times past the barnacles were classed with molluscs be- 

 cause they possessed a calcareous shell, but when their 

 embryology was studied it was discovered that all the early 

 stages were like those of crustaceans, and they have since 

 been classified with other members of that group such as 

 crabs, lobsters, and water-fleas. The former classification 

 for the barnacles was artificial, the latter, it is believed, is 

 more natural. Systematic zoologists are continually striv- 

 ing for a perfect natural classification. 



The animal kingdom is divided into smaller and smaller 

 units just as a military regiment is divided into battalions, 

 companies, platoons, squads, and individuals. The largest 

 groups are called phyla, these are subdivided into classes, 

 etc. In going from larger to smaller, the groups would be 

 arranged as follows : Phylum, Class, Order, Family, Genus, 

 Species. 



Each species of animal is known by its scientific name, 

 which consists of the name of its genus and its own particu- 

 lar species. Taking man as an example, we may classify 

 him. He belongs to the species sapiens and the genus 

 Homo. This genus also includes some other species of 

 men, none of which are now living. The scientific name of 

 man would be, Homo sapiens Linnaeus; the last word 

 showing that Linnaeus first described this particular species. 



