NOTICES OF NEW BOOKS. 395 



also mention Dr. Hart Merriam's important paper (Proc. Biol. 

 Soc. Washington, vol. vii. 1892) " On the Geographical Distri- 

 bution of Life in North America, with special reference to the 

 Mammalia." We find both these, however, included in the 

 useful bibliography given at the end of Mr. Lydekker's own 

 volume, which may be said to be a summary, fairly up to date, of 

 existing knowledge on the subject, and in one respect in advance 

 of the contributions by Messrs. Beddard and W. L. Sclater, who 

 admittedly take but little account of fossil forms. 



In an introductory chapter Mr. Lydekker reviews the schemes 

 of previous writers for the zoological divisions of the earth's 

 surface, and after pointing out what he considers to be defects in 

 the several proposals, concludes by adopting the following modi- 

 fication, in which his three " realms " correspond with what he 

 regards as the " three great evolutionary centres of mammals." 



I. The Notogseic Kealm. — 1. Australian Kegion. 

 ,, ,, 2. Polynesian „ 



,, ,, 3. Hawaiian „ 



„ ,, 4. Austro-Malayan Region. 



II. The Neogseic Realm — Neotropical Region. 



III. The Arctogjjeic Realm. 



— 1. Malagasy Region. 



JJ ;> 



2. Ethiopian ,, 



>> 5) 



3. Oriental „ 



J) )> 



4. Holarctic ,, 



JJ 5> 



5. Sonoran ,, 



The term " Holarctic," it may be observed, was proposed by 

 Dr. Heilprin, at the suggestion of Prof. Newton, to unite Dr. 

 Sclater's Palsearctic and Nearctic Regions under a common title; 

 while the term " Sonoran " is equivalent to Dr. Blanford's 

 " Medio-Columbian " Region. Dealing with these different 

 regions in the order named, Mr. Lydekker proceeds with a con- 

 sideration of their distinctive features, and gives a brief account 

 of the more characteristic mammals to be found therein. In the 

 course of his remarks various interesting problems are discussed, 

 as, for example, the former connection of particular land areas, 

 now widely separated by sea. 



