Living and Extinct Mammalia. 421 



derivation of the Proboscidea ? the Sirenia ? the Cetacea ? or of the 

 Edentata? These are some of the most difficult questions which 

 have to be answered by the modern comparative anatomist and 

 biologist. 



Under geographical distribution the authors have adopted the 

 Zoological regions proposed by Mr. Sclater in 1867, but although 

 there are a few instances recorded of change of distribution due to 

 geological causes in late Tertiary times, we may take it that in this 

 part the fossil evidence is omitted. Thus under the Nearctic region, 

 it is stated, "there are, however, no Perissodactyla," whereas 

 Rhinoceros megalodus has been described by Cope, as well as numerous 

 other Tertiary forms by Leidy and by Marsh. 



We should very much like to see an attempt made to show the 

 geographical distribution of the Mammalia in past times, as well 

 as at the present day. For instance, Dr. Sclater's Palsearctic and 

 Nearctic regions were certainly one, in late Pleistocene times, as the 

 evidence of the Mammalia clearly shows. Thus we have Rangifer 

 tarandus, Alces machlis, Cervus elaphus, and its varieties, Ovibos 

 moschntus, Bison priscus, with the Lemming, Marmot, tailless Hare, 

 Beaver, Fox, Wolf, Otter, White Bear and Brown Bear, the Mammoth 

 and the Horse spread over all these Northern regions alike in the old 

 and the new world, so that these modern geographical regions only 

 represent the torn-up portions of far wider areas formerly connected. 

 The same holds good of the Ethiopian and Oriental (or Indian) 

 regions, the faunae of which even now show such strong marks of 

 affinity the one with the other. 



Professor Flower is one of those who has advocated more strongly 

 than any other Zoologist the importance of incorporating fossil and 

 recent forms together ; but there are not wanting signs in this 

 volume of the difficulties which the authors have felt in attempting 

 this course. In each family the extinct species are carefully kept 

 apart from their recent congeners, a plan which certainly bespeaks 

 the doubts which the authors must have often felt, owing to the 

 imperfect nature of the fossil evidence, of incorporating them in 

 the same series. 



For a Second Edition, which will certainly not be long delayed, 

 we venture to offer the following corrections. Among the Eodentia, 

 to the family Lagomyidce, are given y or f premolars (p. 491), whilst, 

 according to Forsyth-Major, the number of premolars in this family 

 is the same as in the LeporidoB, viz. f , this being the number of the 

 deciduous molars, as observed in Myolagus Meyeri, and M. sardiis ; 

 moreover the statement, "molars rootless," does not apply to all the 

 members of the family, as in Lagodus (Titanomys) , which for this, 

 and other reasons, deserves to rank as a genus distinct from Lagomys, 

 as well as Myolagus, the premolars and molars are both rooted. 



In the small space at our disposal it is impossible to give more 

 than a bare idea of the volume before us. Of its usefulness there 

 can be no question, and we may speedily expect to see French and 

 German editions appearing on the Continent. 



We heartily congratulate the authors upon the successful issue 



