io INTRODUCTION 



the dead languages, Latin and Greek, as these are studied by all 

 civilized nations. Unfortunately many such names are clumsy, 

 and some are barbarous mixtures of Latin and Greek ; but in spite 

 of this the system is a good one. 



The classification of Linnaeus, like that of Aristotle, is a 

 " classification by definition ". As a result of observation, certain 

 groups are defined, i.e. their essential characters are given, and 

 newly - discovered animals are placed in this or that group 

 according as they are found to possess or lack certain features. 

 Such a classification assumes the existence of sharp boundary 

 lines in nature, and is really based on the idea that the different 

 kinds or species of animal were createu separately and inde- 

 pendently. The Linnean Class of Mammals, for instance, is 

 defined as being a group of viviparous animals, possessing a four- 

 chambered heart and hot red blood. Any newly-found kind of 

 animal possessing these features would be considered a mammal. 

 In framing such a classification comparatively few prominent 

 features are selected, and more attention is paid to the boundary 

 lines than to the resemblances between the animals constituting 

 a group. This particular method of subdivision is by no means 

 confined to natural history; an example from another province is 

 afforded by the classification of Britons according to income for 

 income-tax purposes. Those individuals falling well within a sub- 

 division are of no special interest, but those only just coming up to 

 the amount of a particular class are objects of commiseration to 

 themselves as paying a particular percentage with the least reason, 

 while on the other hand those who only just escape falling within 

 a more highly-taxed section have a special interest for the assessors. 



After the time of Linnaeus the rapid progress of more accurate 

 observation, now aided by fairly good microscopes, gradually led 

 to the conviction that classification by definition is far from satis- 

 factory, and to a reaction against the current idea that the different 

 groups of the animal kingdom form a linear series, a gradual 

 ascent from low to high in, so to speak, a straight line. The next 

 important scheme of classification, which we owe to the great 

 French anatomist Cuvier (1769-1832), is one by "type". This 

 system lays stress upon the resemblances between the members 

 of a group rather than on the boundary lines between different 

 groups, or, in other words, " The class is steadily fixed, though 

 not precisely limited; it is given, though not circumscribed; it is 



