I9I4-] SOUTHEASTERN NORTH AMERICA. 165 



tively modern. The family is represented in the Wilcox by the single 

 genus Coccolobis with two species which appear to be the Eocene 

 prototypes of the only two existing arborescent species of Polygona- 

 ceae that reach the United States (the sea grape and the pigeon 

 plum). The genus Coccolobis has about 120 existing species all con- 

 fined to the American tropics and it would appear that it was of 

 American origin. These species range from southern Florida to 

 Mexico, Central America, Brazil and Peru and the majority are 

 coastal forms. The two modern species which are so much like 

 these two ancestral forms in the Wilcox, are strand types found 

 from the Florida keys through the West Indies to the northern coasts 

 of South America, and the conclusion is almost irresistible that the 

 Wilcox forms enjoyed a similar range and an identical habitat. 



The Chenopodiales (Centrospermse of Engler) include ten fam- 

 ilies culminating in the Caryophyllaceas, and containing about 3.500 

 existing species. They appear illy assorted and show a wide range 

 in floral and other morphological characters. Perhaps a majority 

 are modern types. The single family Nyctaginacese represents this 

 order in the Wilcox. 



The Nyctaginaceae with about 150 existing species is predomi- 

 nantly American within the limits of the southern United States on 

 the north and Chile and Argentina on the south. The genus Pisonia 

 Plumier, the only genus thus far found in the Wilcox flora, is repre- 

 sented by three well-marked species. It has about 40 existing spe- 

 cies chiefly in the American tropics and contains the only arbores- 

 cent form of the family found within the United States. It has an 

 extended geologic history, well-marked forms being found in the 

 European and American Upper Cretaceous. The Wilcox species 

 were undoubtedly strand types as are so many of the modern species, 

 which inhabit sea beaches, the shores of salt water lagoons and 

 marshes, the scrub of beach ridges and the jungle behind them. In 

 the existing flora it is associated with Pithccolobium, Reynosia, 

 Metopium, Acacia, Bumelia, Cordia, Coccolobis, Ocotca, Fagara, 

 Mimusops, Conocarpus, Cassia } Eugenia, Anona, Fiats, etc., exactly 

 as it was during Wilcox time. Species of Pisonia occur in the 

 Upper Cretaceous of the Atlantic Coastal Plain (Black Creek forma- 

 tion) as well as in the Middle (Claiborne) and Upper (Jackson) 

 Eocene. 



