172 ANNALS NEW YORK ACADEMY OF SCIENCES 



I'age 



Perissodactyla 2.34 



EquidiP 2.3") 



Tapiridie 238 



RhinocerotidtB 240 



Artiodactyla 241 



riffs and poecarie.s 241 



Ruminants .» 242 



Proboscidea 254 



Sireuia 2.'j6 



Condylartlii-a and specialized successors 2.57 



Edentata 259 



Marsupialia 262 



Monotromata 270 



Summary of the evidence from dispersal of land manmials 270 



Interpretation of negative evidence in fossil mammal faun.-e 27.3 



Dispersal of reptilia 274 



Dinosauria 275 



Chelonia 280 



Crocodilia 284 



Lacertilia 288 



Dispersal of birds 292 



Dispersal of amphibia 294 



Dispersal of fresh-water fishes 297 



General considerations on the distribution of invertebrates and plants. . . . 299 



Interpretation of distribution data of crayfish 301 



Distribution of Helix hortensis 30.3 



Distribution of Percidse 304 



Criticism of some opposing hypotheses 305 



On vain speculations 306 



Summary of evidence 308 



Appendix 311 



Thesis 



1. Secular climatic change has been an important factor in the evolu- 

 tion of land vertebrates and the principal known cause of their present 

 distribution. 



2. The principal lines of migration in later geological epochs have 

 beeii radial from Holarctic centers of dispersal. 



3. The geographic changes required to explain the present distribution 

 of land vertebrates are not extensive and for the most part do not affect 

 the permanence of the oceans as defined by the continental shelf. 



4. The theories of alternations of moist and uniform with arid and 

 zonal climates, as elaborated by Chamberlin. are in exact accord with 

 the course of evolution of land vertebrates, when interpreted with due 

 allowance for the probable gaps in the record. 



