■9I4-] SOUTHEASTERN NORTH AMERICA. 137 



It is obvious that the flora could not have existed if the region was 

 ever visited by frost, and temperatures appear to have been like those 

 found today on the Florida keys. Aside from the meteorological 

 certainty that there was a wide coastal belt of abundant precipitation, 

 there is the confirmation furnished by the flora itself. It would seem 

 to me proper to compare the Wilcox flora with those of the regions 

 to which the somewhat loosely used term subtropical rain forest is 

 applied by plant geographers. Too little is known of the -Midway 

 flora for accurate comparisons. Compared with the Upper Cre- 

 taceous flora of the embayment area, in which however 40 percent 

 of the genera are extinct, the Wilcox would seem to have become 

 more tropical, a progression from what might be termed a warm 

 temperate to a subtropical rain forest. On the other hand the floras 

 as well as the faunas show a gradual increase of tropical conditions 

 in the later Eocene which culminate in the Oligocene, the flora of 

 which in southeastern North America is strictly tropical. 



Lianas were apparently not as common in the Wilcox as they 

 are in the existing floras with which it has been compared. No 

 traces of the Bignoniaceas, so common in the American tropics, have 

 been detected, the scandent types being represented by Lyg odium, 

 Aristolochia, Malpighiaceae, Canavalia, Pisonia (?), and Zizyphus, 

 I am inclined to think that the great uniformity of climatic condi- 

 tions together with the abundant rainfall have combined to make the 

 Wilcox flora seem more tropical in character than was actually the 

 case. That reef corals are not found in the Wilcox is, I believe, en- 

 tirely due to physical conditions other than those of temperature 

 as Yaughan- has shown to be the case so often in such a striking 

 manner in recent seas. 



1 have indicated upon the sketch map (Fig. 1 C-C) what I con- 

 ceive would be the northern limit of range of the Wilcox flora under 

 existing climatic conditions in southeastern North America. 



It would seem to be probable that most of the generic types of 

 the Wilcox were differentiated by the close of the Cretaceous. If the 

 equatorial region of America was the place of origin of a majority of 

 those types which have not as yet been recorded from the Cretaceous 

 as I believe to be the case, they must have spread northward along 



2 Yaughan, T. \V., Jouni. Wash. Acad. Sci., Vol. 4, pp. 26-34, IQM- 



