REVIEWS 559 



among the numerous elementary botanical works already in existence, and it 



certainly deserves to take high rank, for the authors have spared no pains over 



its production and have in consequence given us a thoroughly good " introduction 



to the study of plants." The book is extremely well got up, and its price is very 



reasonable. 



F. C. 



A History of Land Mammals in the Western Hemisphere. By W. B. Scott, 

 Ph.D., D.Sc, LL.D. [Pp. xii + 693, with 32 plates and 272 other figures.] 

 (New York : Macmillan & Co., 1913. Price 21s. net.) 



America, and especially North America, has extensive fossil beds, which during 

 the last three decades have yielded an astonishing variety of animal remains. 

 They have been worked at by a number of investigators, and the past history of 

 the continent itself and certain of the animal groups that have dwelt in it can now 

 be outlined with some degree of certainty. In this book we have a review of the 

 present position of mammalian palaeontology in the United States by one of its 

 leading workers and most able exponents. 



The opening chapters deal with geological and palaeontological methods, and 

 a description of the most striking features of the mammalian fauna of the continent 

 to-day. These are followed by a brief account of the various alterations that have 

 taken place in the land area and the changes in the mammalian groups accom- 

 panying them. 



The larger part of the book deals with the history of the main groups of the 

 mammalia ; a most fascinating series of stories, to which the first part of the book 

 furnishes a complete introductory guide. Naturally the various groups are most 

 unevenly represented by fossil remains. It is obvious that solitary forest dwellers 

 or small arboreal forms did not stand as good a chance of preservation as the 

 herbivores that roved the plains in vast numbers. The carnivores, too, although 

 some forms may have hunted in packs like wolves, were mostly solitary, and could 

 never have been as numerous as the animals upon which they preyed. These 

 difficulties, and the obvious imperfection of the geological record, render some of 

 the histories exasperatingly short and incomplete ; but, brief though they are, 

 they are full of interest. The accounts are given in a clear and concise manner, 

 and, as the author starts with the forms as we know them to-day, and traces 

 them backwards through less and less familiar ones, they are most easy to follow. 



It is remarkable that horses passed through a large part of their development 

 in North America, and yet the immediate ancestors of the horses now found there 

 must be sought for in Europe, as the stock appears to have died out completely. 

 Perhaps more strange is the fact that in all probability the camels also originated 

 there, and did not leave until late Miocene or early Pliocene times. On the other 

 hand, the elephants came from the old world to form a conspicuous feature in the 

 mammalian fauna from late Miocene to Pleistocene times. They originated in 

 the old world, and in tracing their story the author judiciously incorporates the 

 facts of their early development, whose discovery in Egypt we owe to Dr. 

 Andrews. 



Much though we know of some families, far more remains to be discovered, 

 and Prof. Scott's book should prove an inspiration to further efforts, particularly 

 to palaeontologists in his own land, who owe him a deep debt of gratitude. 



The outline of classification given on p. 59 is in the main a good one, but the 

 reasons adduced for separating infra-classes Didelphia and Monodelphia are 

 obsolete. It is stated on p. 58, and again on p. 629, that the Monodelphia are 



