INTRODUCTORY 15 



The arrangement and nomenclature followed are those 

 adopted by Flower and Lydekker in their recently-publislied 

 " Introduction to the Study of Mammals," with this excep- 

 tion, namely, that I begin with the Chiroptera and end with 

 the Cetacea, instead of the reverse, the result being that the 

 orders are presented in the same sequence as in the second 

 edition of Bell's " History of British Quadrupeds," which is 

 still the standard work on these animals. The following 

 quotations from Flower and Lydekker's book are well 

 worth bearing in mind in this connection. The authors 

 remark, p. 84, that " In systematic descriptions in books, 

 in lists, and catalogues, and in arranging collections, the 

 objects dealt with must be placed in a single linear series. 

 But by no means can such a series be made to coincide 

 with natural affinities. The artificial character of such 

 an arrangement, the constant violation of all true relation- 

 ships, are the more painfully evident the greater the 

 knowledge of the real structure and affinities. But the 

 necessity is obvious, and all that can be done is to make such 

 an arrangement as little as possible discordant with facts." 

 Again (p. 85), speaking of the sub-class EiUheria {Mono- 

 delphia), with which alone we have here to do, they make the 

 following observations : — " Their affinities with one another 

 are so complex that it is impossible to arrange them serially 

 with any regard to natural affinities. Indeed, each order is 

 now so isolated that it is almost impossible to say what its 

 affinities are ; and none of the hitherto proposed associations 

 of the orders into large groups stand the test of critical 

 investigation. All serial arrangements of the orders are 

 therefore perfectly arbitrary ; and although it would be of 

 very great convenience for reference in books and museums 

 if some general sequence, such as that here proposed, were 

 generally adopted, such a result can scarcely be expected, 



