I9I4-] SOUTHEASTERN NORTH AMERICA. 177 



and abundantly represented in European Tertiary floras. Its Cre- 

 taceous ancestry is hidden among the species of leaflets referred to 

 the form-genus Lcgumino sites. The genus Mimosa which is ap- 

 parently most like the Wilcox Mimosites, has over 300 existing spe- 

 cies and these are for the most part confined to the warmer parts of 

 America, although they are represented in Asia, Africa and Aus- 

 tralia. 



Except for the family Lauracese the Caesalpiniacese with 26 spe- 

 cies is the largest family in the Wilcox flora and it is certainly a fact 

 of considerable interest that the massing of the modern species in 

 the American tropics should be foreshadowed by their numerical 

 abundance on this continent as early as the Lower Eocene. 



The Wilcox genera are five in number of which the largest is Cassia 

 with twelve species. Cassia is the largest Wilcox genus except Ficus > 

 and all of its species find their modern counterparts in existing species 

 of tropical and subtropical America, many of which are mentioned by 

 name in the systematic part of this work. Numerous as are the 

 Wilcox species of Cassia there was apparently greater specific differ- 

 entiation in contemporaneous European deposits since Ettingshausen 

 records 15 species in the flora of Alum Bay (Ypresian of Isle of 

 Wight). Cassia has between three and four hundred existing spe- 

 cies found in the warmer temperate and tropical regions of all the 

 continents and especially abundant in tropical America. Their place 

 of origin is unknown since they make their appearance in the Upper 

 Cretaceous almost simultaneously in New Zealand, Australia, Bo- 

 hemia, Saxony, Greenland, the Atlantic Coastal Plain and the 

 Dakota Group of the Rocky Mountain province. Upwards of one 

 hundred fossil species are already known. Nor does the Eocene 

 distribution shed any light on the early history of the genus since 

 species occur in such widely separated regions as North America, 

 Europe and Australia. There are numerous Oligocene and Miocene 

 species, the Oligocene records being confined to Europe and Africa 

 and the Miocene records being confined to Europe and North Amer- 

 ica. Cassia was abundant along the shores of the Pliocene Medi- 

 terranean of Europe and 4 species are recorded from South American 

 beds which are thought to be of Pliocene age. Pleistocene species 



PROC. AMER. PHIL. SOC, LIII,, 214, L, PRINTED JULY II, I9I4. 



