150 NATURAL HISTORY. 



fore similar to one another in the general form of the 

 body and in certain other external features. 



On the other hand, Cuvier showed that, as regards their 

 whole organisation, and more especially as regards their 

 anatomical structure, the whales and dolphins are related, 

 not to the fishes, but to the ordinary quadrupeds, and 

 that therefore they should be regarded as a group of 

 Mammals specially modified for an aquatic life. Acting 

 upon this principle, we may say with Owen that 

 'the characters of the classes of animals have been 

 rendered by the immortal Cuvier, the highest expression 

 of the facts ascertained in the animal organisation.' It 

 is not meant by this, of course, to assert that Cuvier's 

 classification was by any means perfect, for we have 

 seen that it was not ; nor that he was always correct in 

 his views as to the facts concerning the anatomy of 

 animals ; nor even that he always applied his own 

 principles strictly. An absolutely perfect classification 

 will only be possible when we are acquainted with all 

 the facts as to the organisation of every animal in 

 other words, it will never be possible. All that can be 

 asked of a classification is, that it should be the formal 

 expression of the known facts of comparative anatomy 

 at the time when it was drawn up. Cuvier recognised 

 the true principles of all philosophical classification, and 

 being admittedly the first comparative anatomist of his 

 day, he was able to construct a classification of the 

 animal kingdom which was an immense advance upon 

 anything that had preceded it, and the main outlines 

 of which still endure. Since Cuvier's time, however, 

 comparative anatomy has made incalculable strides, and 



