110 



LOWER EOCENE ELORAS ()!•' SOUTHEASTERN NORPU AMERICA. 



based ou the petrified ■wood in the overlying 

 Claiborne of Texas. 



Tlie genus Bercheniia Xecker eontains about 

 a dozen existing species, 10 of wliicli are con- 

 fuied to eastern and southeastern Asia, 1 lives 

 in eastern extratropieal North Anieriea, and 1 

 in eastern Africa. This distribution could not 

 have been brought about except by the agency 

 of a cosmopolitan Tertiai'y range. Though the 

 specific differentiation of Berchemia is limited 

 to 5 or 6 fossil forms, these are very common 

 and have a wide range. The earliest occur- 

 rences are in North America and include the 

 Raton, Denver, and Fort Union formations of 

 the Rocky Mountain province. The genus 

 makes its appearance in Europe during the 

 Ohgocene and is common tlu-oughout that 

 region in the Miocene, becoming restricted to 

 southern Europe (France, Italy, Sicily, and 

 Slavonia) dvu'ing the Pliocene, except for a form 

 recorded by Reid from Limburg. 



A species of HoveniphyUum, supposed to 

 represent the existing genus Hovenia Thun- 

 berg, which includes a single existing species 

 in southeastern Asia, is found in the Plio- 

 Pleistocene of Japan. The genus Colubrma 

 Brongniart, which contains 15 existing species 

 in tropical .Vmerica and 1 m southeastern Asia, 

 is recorded from the Miocene of Bohemia. 



The genus Pomaderris Labill, which con- 

 tams about 24 existing species confined to 

 Australia and New Zealand, is represented by 2 

 species in the Tertiary of Australia and 3 species 

 (Pomaderrites Ettingshausen) in the Miocene 

 of Prussia, Bohemia, and Styria. 



The genus Gouiana has 2 species in the 

 Tertiary of Colombia, according to Engelliardt. 



The genus Ceanothus Linne, which comprises 

 about 40 existing species that are confined to 

 North America, has been made to include nu- 

 merous fossil species subsequently referred to 

 Paliurus or Zizyphus. There are 4 species 

 recorded from the Upper Cretaceous of Green- 

 land, New Jersey, Vancouver Island, and 

 Westphalia; 2 Eocene species from Greenland 

 and British Columbia; a Miocene species from 

 Prussia, Switzerland, and Italy; and a Pleisto- 

 cene species in Kentucky. 



The next order, the Malval(>s, includes 9 

 famUies and about 1 ,80() existmg species. The 

 Tiliacese, Sterculiacese, and Bombacaceaj arc 

 the only families represented in the Wilcox 



flora. The largest modern family, the MaJ- 

 vaccic, which contains more than 800 species, 

 many of which are lierbaceous and range fronr 

 6.5° nortli latitude in Russia to 45° south 

 latitude in New Zealand, is not represented in 

 the Wilcox. The order displays somewhat 

 uneven or but little understood phylogenetic 

 charactera, but is evidently allied to the suc- 

 ceeding order, tlie Parietales, tlirough the 

 family Elieocarpacese. These inequalities of 

 evolution are shown, among other ways, by the 

 complete syncarpy in the Tiliacea?, associated 

 with an indefinite number of stamens and by 

 the complex arrangement of the stamens in 

 the Sterculiacete, associated with more or less 

 incomplete union of the carpels. Both the 

 leaves, flowers, and fruits exhibit a wide range 

 of variations tlii'oughout the order. 



The family Tdiaceie, represented in the Wil- 

 cox flora by a single, not very common form 

 of Grewiopsis, uacludes about .35 genera and 

 370 existing species, mostly of tropical lands, 

 and shows two centers of differentiation and 

 distribution — one the area surrounding the 

 Indian Ocean and the other in northern South 

 America. The geologic history is chiefly con- 

 fined to the four genera Tilia (or Tilia'phyllum), 

 Grewia, Grewiopsis, and Apeibopsis. The ge- 

 nus Luhea has been described from the Eocene 

 of Sezanne (Langeron) and from the Oligocene 

 of Menat (Laurent), both French localities, and 

 also from the Tertiary of Ecuador. The genus 

 Tilia Linne, wliich includes 18 or 20 widcW 

 distributed existing species in the North Tem- 

 perate Zone, exclusive of western North America 

 and central Asia, has furnished about 25 fossil 

 species based on both leaves and fruits. The 

 oldest knowm species comes from the North 

 American Eocene. There are no conclusive 

 Oligocene records except two French species, 

 but about 15 Miocene species are found in 

 North America, Europe, Asia, and the Arctic 

 regions. There are 5 Pliocene species recoi-ded 

 from Europe and Japan and 6 Pleistocene 

 species from Ontario, New Jersey, France, 

 Germany, IloUand, and Denmark. The exist- 

 ing range of the genus apparently dates from 

 Miocene time. 



The; genus Grewia Linne includes about 90 

 existing species that range from Arabia to 

 China and Japan and through Malaysia to 

 Australia, and frdin Abvssinia to South Africa, 



