6$ Notices respecting New Books. 



cent ages of time found from the theory of a cooling globe, there is 

 a remarkable agreement, and strongly justifies the principle held 

 by many geologists, that the proper relative measure of geological 

 periods is the maximum thickness of the strata formed during 

 those periods. 



The fourth and fifth lectures are devoted to the distribution 

 and origin of the rivers and lakes of Europe, Asia, S. America, and 

 Africa, including details as to their drainage-areas, rate of denuda- 

 tion of the different rain-basins, and matter discharged by the 

 rivers. Orographical maps of the two latter continents are given, 

 in order to show the great superiority of S. America over Africa in 

 the manufacture of rivers, as fully explained (pp. 204-243). 



The geographical distribution of animals and plants forms the 

 subject of the concluding lecture, in which the author gives an out- 

 line of the more important facts, and the attempts that have been 

 made to explain them. The groups of animals selected for illustra- 

 tion are the King-Crabs, Ostrich family, non-placental Mammals, the 

 Edentates, Humming-birds, and the Monkeys and Apes. The dis- 

 tribution of the subdivisions of the above groups is given, as also 

 of their fossil ancestors as bearing on the origin of the present 

 forms. 



The zoological regions are adopted from Mr. "Wallace, but with 

 different names, viz. the Europasian, N. and S. American, African, 

 Australian. These five natural regions are related to the ancient 

 land-systems of the globe defined by the meridian axes of elevation, 

 of which there are two in the northern and three in the southern 

 hemisphere, as described by the author (pp. 20, 29), and which date 

 back as far as the earliest sedimentary deposits, modified, as in the 

 case of Europasia, by an east-and-west small-circle chain, which is 

 only of Tertiary origin. The characteristic animals of these differ- 

 ent zoological provinces are given, and their relation to the pre- 

 glacial fauna of the same regions. 



To the above five regions an Oriental, or supplemental one is 

 added, as it does not owe its origin or fauna to any of the primary 

 continents of the northern or southern hemisphere, but seems to 

 have been supplied by immigration. It contains all tropical Asia 

 east of the Indus, with the Malay islands as far as Java, Borneo, 

 and the Philippines. 



In the geographical distribution of plants the author follows 

 Bentham, who recognizes three great floras, the Northern, Southern, 

 and the Equatorial Tropical. Details of the characteristic forms of 

 these floras are given ; but with regard to the entire flora of the globe 

 having one origin only, as believed by some botanists, he consi- 

 ders it to have had two origins, from both poles (pp. 288, 313). 

 A comparison of the present and Miocene floras and climates of 

 the Arctic regions concludes this lecture (pp. 313-345). From 

 the facts stated, it is inferred : — 



1. The Miocene July temperature of G-rinnell-land, Spitzbergen, 

 was 28° F. higher than at present. 



2. The Gulf-stream, which is now the cause of the difference 



