76 



LOWKR EOCICXE FLOHAS OF tiOUTIlEASTF.IiX XOItill AMEKKA. 



occurs ill a region of bayous and lagoons, as 

 shown by the scchmcnts. 



The ("ycailacctr, wliich vrcrc ])racticaUy cos- 

 inopohlan during the Mesozoic era, are ahnost 

 luiknown in the Tertiary period, despite the 

 fact that there are 9 still existing genera to- 

 gether containing over 100 species. The Ter- 

 tiary records inchide a doubtfully deterniiii('(l 

 Zamites from the Heersian of Belgium, an 

 Oligocene species from southeastern P'rance, an 

 early Tertiary species from Chile, a late Oligo- 

 cene Encephalartos-like form from Greece, and 

 two poorly defuied species from the Miocene 

 of Switzerland. The Wilcox land would seem 

 to have furnished ideal conditions for Zamia- 

 lilie forms, but material of this sort is veiy rare 

 and is confuied to the later Wilcox of the west- 

 ern embayment area. This scanty material is 

 very similar to the existing Zantia puin'dd 

 Linne, a small species with an imderground 

 stem common in the hammocks of the cast 

 coast of Florida. The genus contams about 

 30 existing species confined to the tropic and 

 subtropic regions of America. 



The j\jigiosperm£e, decidedly the dominant 

 class in existing floras, was as clearly dominant 

 in Wilcox time, since to it belongs more than 

 94 per cent of the knowai Wilcox flora. Of 

 these numerous angiosperms only nine are 

 referable to the Monocotyledona^. It is true 

 that the number of monocotyledons might 

 have been increased by describing the various 

 sedge or grasslike fragments that are not un- 

 common at certain localities. However, none 

 of these fragments have been dignified by 

 names except a suigle form each of Poacites 

 and Cyperites, which were retained only be- 

 cause they were already in the literature. 

 That only three species of palms have been 

 recognized is remarkable, for palms were well 

 difTerentiated at this time and genera such as 

 Phcenicites, Thrinax, Geonoma, Bactrites, and 

 Manicaria are recognized in the later Tertiary 

 deposits. Of the 30 monocotyledons named 

 l)y EttingsliaTisen' in the contemporaneous 

 deposits of Slicppey 22 species are palms. On 

 the other hand, the contemporaneous Alum 

 Bay flora, which comes from a locality not far 

 distant from that of the Sheppey deposits, fur- 

 nishes only 6 monocotyledons. This contrast 

 indicates that the fruits which accumulated at 



• Roy. Soc. London Proc, vol. 29, p. 393, 1879. 



Slie])pey in the delta of an Eocene river system 

 contain interior forms not present in the coastal 

 region, repi-esente(l by tlie Alum Bay clays, and 

 that inland from tlie Wilcox coast monocotv- 

 ledons suitable to the AVilcox envii-onment 

 flourished but were not preserved as fossils. 



Since the early Eocene floras of Europe arc 

 so nuieli like those of southeastern Xorth 

 America an enumeration of tlie Sheppi'v jiahns 

 is of considerable interest. They include tlie 

 genera Xij)a, rEnocar])Us, Areca, Iriartea, 

 Livistoiui, Sabal, Chama^'ops, Thrinax, Bac- 

 tris, Asterocaryum, and EUeis. Of thes(> Nipa 

 and Sabal are represent<'d in the Wilcnx and 

 Thrinax and Bactrites are jiresent in the em- 

 bayment area in the middle Eocene (Claiborne). 

 The order Palmales, or more ])ro]K>rly Arecales, 

 has a single existing family, the Arecaceje 

 (Palnisr), with about 150 genera and consid- 

 erably more than a tliousand existing species, 

 about equally divided between the oriental and 

 occidental tropics. There are no temperate 

 outliers, although some species extend far into 

 the Temperate Zone, as for examjile Sahdl adan- 

 sonil, whicli ranges northward along the Atlan- 

 tic coast as far as Xorth Carolina. The present 

 distribution of the palms is a good illustration 

 of modern continental floral diversities succeed- 

 ing a Tertiai'v cosmopolitanism of floras, and 

 it shows further the jiart i)layed by isolation in 

 evolution, which is also indicated by the abun- 

 dance of monotypic genera in the Orient, where 

 the tropical area is so much broken. Not a 

 single species or genus is common to the two 

 hemispheres and even the tribes are almost all 

 either oriental or occidental. 



Most students regard the PandanaccEe (screw 

 pines) as the probable ancestral stock of tiie 

 pahns, and thtnigh the screw pines are entirely 

 oriental now, they were not so in the Tertiary, 

 and it is perhaps significant that the existing 

 genus Phytelej)has, which is regarded as inter- 

 mediate between the Pandanacea^ and the Are- 

 cacetB is exclusively ^Vmerican, and that genera 

 now exclusively oriental are represented in tiie 

 American Tertiary, X^ipa in the Wilcox and 

 Phoenix in the Vicksburg. There is no warrant 

 for the assertion that ]ialms are of occidental oi- 

 igin, but their oriental origin is e(|ually didicult 

 of proof, and what wi; know of their geologic 

 history clearly shows that their existing distri- 

 bution throws little light on tiieir plulogeny. 



