INTRODUCTION 5 



these creatures, along with Snails, Mussels, and the like, in 

 the group Mollusca, and even the great anatomical skill of 

 Cuvier failed to show their true position, which was made 

 out only when Vaughan Thompson, about fifty years ago, 

 proved, from a study of the newly hatched young, that 

 their proper place is among the Crustacea, in company with 

 Crabs, Shrimps, and Water-fleas. 



Given a sound knowledge of the anatomy, histology, and 

 embryology of animals, their Classification may be attempted 

 that is, we may proceed to arrange them in groups and 

 sub-groups, each capable of accurate definition. 



The general method of classification employed by 

 zoologists is that introduced by Linnaeus, and may be 

 illustrated by reference to the group of Cats which we have 

 already used in the explanation of the terms genus, species, 

 and variety. 



We have seen that the various kinds of true Cat 

 Domestic Cat, Lion, Tiger, &c. together constitute the 

 genus Felis. Now there is one member of the cat-tribe, the 

 Cheetah, or Hunting Leopard, which differs from all its 

 allies in having imperfectly retractile claws and certain 

 peculiarities in its teeth. It is therefore placed in a distinct 

 genus, Cynalurus, to mark the fact that the differences 

 separating it from any species of Felis are of a more 

 fundamental character than those separating the species of 

 Felis from one another. 



The nearest allies of the Cats are the Hyaenas, but the 

 presence of additional teeth and non-retractile claws to 

 mention only two points makes the interval between 

 Hyaenas and the two genera of Cats far greater than that 

 between Felis and Cynaelurus. The varying degiee of 

 difference is expressed in classification by placing the 

 Hyaenas in a separate family, the Hycenidcr, while Felis and 



