120 



LOWER EOCENE FLORAS OF SOUTHEASTERN NORTH AMERICA. 



aiul to which it has since been so Lufiely con- 

 fineil. The types peculiar to the Austrahan 

 region represent the rehcs of th(> (Vetaeeous 

 radiation and iiu-huU^ nnincnous new types 

 evolved on that continent, as Anth-ews has sug- 

 gested. This is exactly tiie reverse of the 

 hypothesis proposed by Deaue,' but one that 

 accords far better with the facts not only of 

 geologic history but vv'ith those of existmg dis- 

 tribution. 



As is pointed out in the systematic part of 

 this work all the Wilcox forms are coastal types 

 closely related to existmg American species of 

 similar habitat. 



About 150 fossil forms have been referred to 

 the Myrtacepe, one-third at least having been 

 described as species of Eucalyptus. At least 

 haK of these forms occur in the Cretaceous of 

 all parts of the world but particularly through- 

 out the Northern Hemisphere. They are es- 

 pecially well represented in North America, 

 and the possibility that they are ancestral 

 forms of M>Tcia or Eugenia has already been 

 pointed out. A similar widespreatl distribu- 

 tion but less specific variation characterizes the 

 Eocene forms that have been referred to Eu- 

 cal3^ptus. The Oligocene records are all Euro- 

 pean and the Miocene records include both 

 Europe and Asia. 



The genus Myrtus is represented by about 24 

 fossil species, all European, most of them al- 

 most equally divided between the Oligocene 

 and the Miocene. The oldest forms are early 

 Eocene, but the form genus Myrtophyllum 

 lieer includes several Upper Cretaceous species 

 in Europe, America, and Australia, as well as 

 Tertiary species in Europe, Asia, and South 

 America. 



The genus Myrcia De CandoUe, so well rep- 

 resented in the Wilcox flora, contains species 

 in the European Oligocene, 4 species in the 

 early Tertiary of Chde, 1 in the Tertiary of 

 Ecuador, and 1 in the Pliocene of Brazil. 



Tlie oldest known s[)ecies of Eugenia, a genus 

 also prominent in the WUco.x flora, occurs in 

 the Dakota sandstone. The genus is repre- 

 sented in Europe throughout the Tertiary 

 from the lower Eocene to the Pliocene and is 

 recorded fi'om the Tertiary of Ecuador. 



The genus CaUistemon R. Brown has been 

 identified in both the Upper Cretaceous and 



1 Deane, H., op. cit. 



Tertiary of Europe, and no less than 25 spe- 

 cies have been referred to the genus Callistenio- 

 pliylimu Ettingshausen. These species include 

 Upper Cretaceous forms in America and Eu- 

 rope, Eocene forms in Greeidand, Oiigocen(^ 

 forms in Australia, and numerous Oligocene and 

 Mioc(Mie species in Europe. 



The genus Myrciaria Berg, often inchuU'd in 

 Eugenia, contains about 60 existing species 

 ranging from the West Indies to Brazil and 

 Peru. It is recorded by Engelhardt from the 

 Tertiary of Ecuador. 



Leptospermum, L(>ptospermites, and Lep- 

 tospermoearpum have been identified from the 

 Upper Cretaceous and Tertiary of Europe; 

 Tristania-like fruits have been described as 

 Tristanites by Saporta froni the lower Miocene 

 of France, and by Kitson from the Miocene of 

 Australia; the genus Psidium Linne, which in- 

 chuU's al)out 100 modern species in the West 

 Indies and Mexico, is represented in Chile by 

 an early Tertiary species; and finally the genus 

 Metrosideros has been identified in the Atane 

 beds of Greenland and in both the Oligocene 

 and Miocene of Europe. 



The family Combretaccie (Terminaliacea") 

 embraces about 16 genera and 285 existing 

 species of shrubs or trees and tropical vines 

 that bear simple, entire, coriaceous, persistent, 

 exstipulate, alternate or opposite leaves. The 

 inflorescence is racemose or capitate, and the 

 flowers are regular, perfect or polygamous, 

 many of them apetalous. The stamens are 

 two or tlu-ee times as numerous as the petals 

 and the one-celled ovary develops into a drupa- 

 ceous or berry-like indehiscent fruit, in many 

 species crowned with the accrescent calyx, and 

 containing a solitary seed without endosperm. 



The e.xisting species are all tropical or sub- 

 tropical, ranging from 34° north latitude to 

 35° south latif utle, and a relatively large num- 

 ber are littoral or strand types. The conti- 

 nental areas contain the following numl)ers of 

 peculiar species: America 75, Africa 85, Mada- 

 gascar 36, Asia 57, Australia 23. About ten or 

 a dozen species ari^ found in more than one 

 area. There is a remarkable identity between 

 the American tropics and those of West Africa, 

 the genera Caeoucia, Conoc^arpus, and Lagun- 

 cularia having identical species in both regions. 



The geologic history of the family is most in- 

 complete, but it is exceedingly prominent in 

 tlie Wilcox flora, where it is represented not 



