CLASSIFICATION OF THE MAMMALIA 51 



without devising an artificial terminology, drawn chiefly from 

 Greek and Latin. 



In dealing with fossils, the difficulty of nomenclature be- 

 comes formidable indeed. The larger and more conspicuous 

 mammals of the modern world are more or less familiar to all 

 educated people, and such names as rhinoceros, hippopotamus, 

 elephant, kangaroo, will call up a definite and fairly accurate 

 image of the animal in question. For the strange creatures 

 that vanished from the earth ages before the appearance of 

 Man there are no vernacular names and it serves no good pur- 

 pose to coin such terms. To the layman names like Uinta- 

 therium or Smilodon convey no idea whatever, and all that can 

 be done is to attempt to give them a meaning by illustration 

 and description, using the name merely as a peg upon which 

 to hang the description. 



The system of zoological classification which is still in use 

 was largely the invention of the Swedish naturalist Linnaeus, 

 who published it shortly after the middle of the eighteenth 

 century. As devised by Linnaeus, the scheme was intended 

 to express ideal relationships, whereas now it is employed to 

 express real genetic affinities, so far as these can be ascertained. 

 The Linnaean system is an organized hierarchy of groups, 

 arranged in ascending order of comprehensiveness. In this 

 scheme, what may be regarded as the unit is the species, a 

 concept around which many battles have been waged and 

 concerning which there is still much difference of opinion and 

 usage. Originally a term in logic, it first received a definite 

 meaning in Zoology and Botany from John Ray (1628-1705) 

 who applied it to indicate a group of animals, or plants, with 

 marked common characters and freely interbreeding. Linnaeus, 

 though not always consistent in his expressions on the subject, 

 regarded species as objective realities, concrete and actual 

 things, which it w^as the naturalist's business to discover and 

 name, and held that they were fixed entities which had been 

 separately created. This belief in the fixity and objective 



