MATTHEW, CLIMATE AND EVOLUTION 291 



data themselves indicate and what is assumed as true from other evidence. 

 He concludes, — 



1) That the species are the product of their environmental conditions; 



2) That their dispersal center was in western Mexico, whence they have 

 spread northeast as far as Texas and Florida, southwardly into South Amer- 

 ica, northwestwardly into Lower California ; 



3) That the primitive type was nearest the Texas and Floi'ida species. 



He assumes — evidently on some other grounds — 



1) That a great land area stretched out from Mexico far into the Pacific 

 during the Tertiary all the way between Lower California and Central 

 America ; 



2) That the central tableland of Mexico was a vast fresh- water lake during 

 most of the Tertiary ; 



3) That Cuba was connected with the American mainland during the Oligo- 

 cene (this assumption underlies the statement that, since the Floridian Cnemi- 

 dophorus did not reach Cuba, its migration must have occurred as late as 

 Miocene). 



Ortmann/^° reviewing tliis paper, takes, as proven by Gadow's studies, 

 not merely the points actually indicated but also the assumptions which 

 are entirely unnecessary to explain the data but which Dr. Gadow evi- 

 dently feels obliged to take for granted. In fact, these assumptions 

 interfere with a reasonable interpretation rather than help it, and all 

 of them are questionable, to say the least. The great Tertiary lake is, 

 I suspect, on all fours with the vast interior '^'lakes'' of the Plains region 

 of the United States, which the progress of physiographic and paleon- 

 tologic studies have relegated to the domain of m3'i;h. The connection 

 of Cuba with the mainland of either North or South America involves 

 the same difficulties as the connection of Madagascar with Africa. The 

 recent discoveries by Dr. de La Torre of a Pleistocene vertebrate fauna 

 in Cuba strongly confirm this analogy between the Cuban and Malagasy 

 faunas. The existence of extensive land west of the present Pacific coast 

 line is an equally unnecessary and improbable hypothesis. On the other 

 hand. Dr. Gadow fails to take into account the barrier between North 

 and South America which prevented or hindered intercommunication of 

 land faunas during a large part of the Tertiary, while it permitted inter- 

 communication of marine faunae during the Eocene. I am not here 

 concerned with its nature but may venture to point out that its bearing 

 on the differentiation of species would be important. For, once across 

 that barrier, an invading species would find itself in unfamiliar environ- 

 ment on account of differences in the autochthonic fauna and flora, even 



^ A. B. Ortmanx : Geog. Jahrb., vol. xxxi, p. 262. 1908. 



