COMI'dSTTIOX OK Tirr-. FLORA. 



109 



Greenland. In Europe only a sini^lc species is 

 recorded from the Paleocene. The Ypresinii, 

 which is synclii'onous with the Wilcox, eontiiins 

 3 species in the south of Eni;;lan(l. 



There are 1 1 or 1 2 Oligocene species in l-iance, 

 Prussia, Tyrol, Italy, Dalmatia, Styria, and 

 Greece and a single undescribed species in (lie 

 Apalachicola group of Florida. There ai-c 

 more than two score species in tiie Miocene of 

 Switzerland, ItiiJy, Bohemia, Prussia, and 

 Styria, llhamnus being es])eclally al)un(huil. 

 It is also found in the Miocene of Iceland, 

 Spitz])ergen, Manchuria, and the island of 

 Saklialm. In this continent there arc species hi 

 British Cohunbia and in (\)lorado. 



There are about 13 Pliocene species, of which 

 no less than 9 are recorded from Italy and 1 

 from the island of Java. There is an extinct 

 species in tlie Pleistocene of Himgary and a 

 still-existing species m the Pleistocene of the 

 island of Madeh-a. In addition to the species 

 referred to Rhamuus the form genus Rham- 

 nites Forbes, founded on 3 species from the 

 Eocene of the Isle of Mull, contains 2 Ameri- 

 can Upper Cretaceous species fountl ui the 

 Karitan, Tuscaloosa, Magothy, and Dakota 

 formations. A species occurs in the Fort 

 Union and another hi tlu? Wilcox. The genus 

 llhamnacuiiuni of Felix is based on petrified 

 wood. It contains 5 or 6 species found in the 

 Eocene of the Caucasus, Texas, and vSaskatche- 

 wan, and in the Miocene of Yellowstone Park. 



The genus Paliurus Jussieu, which includes 

 only 2 existing species, rangmg from southern 

 Europe through southern Asia to C^hina and 

 Japan, was cosmopolitan in former times. 

 More than 40 fossil species have been described. 

 At least 12 are known from the Upper Creta- 

 ceous, all confined to North America. There 

 are 2 species each in the Karitan, Magothy, and 

 Laramie; 5 m the Dakota; and 1 each in the 

 Eutaw formation of Georgia, m western Green- 

 land, and Vancouver Island. There ar(> 10 

 Eocene species, also confined to North Amei'ica, 

 2 of them found in the Fort Union and .'J each 

 m the Denver, in western Greenland, and in the 

 Wilcox. The leaves are rare hi the Wilco.x, 

 but the characteristic peltate fruits are not 

 uncommon. The oldest Euro))ean forms an> 

 2 species m the Oligocene of France, and a well- 

 marked species is contained in the Oligocene 

 (Vicksburg group) of Louisiana. The 13 



Miocene species are found in Asia (Siberia and 

 Sakhalin), Europe (Switzerland, Baden, Ger- 

 many, Bohemia, Italy, St^Tia, and France), and 

 North America ((^olorado and Oregon). The 

 ])reseiice of numerous species of Paliurus in the 

 Upper Cretaceous and Eocene of North America 

 :uid their absentee on other continents befor(> the 

 Oligocene rendci's it very ])rol)a])le that the 

 g(>nus originated in tlu^ Western Hemisphere. 



Tlie genus Zizyphus Jussieu, which contains 

 about 10 existing spcH'ies, largely shrubs, manv 

 of them prosti'ate or scrambling, and a, few 

 small trees, is mostly Indo-Malayau in its dis- 

 tribution but is represented by a few species in 

 the tropics of Eastern Asia, America, Africa, 

 and Australia. Tli(> naturalized Ziz>jp]riis viil- 

 (/(iiis forms extensive thickets in some localities 

 in southeast(M'n Louisiana,. There are more 

 than 50 known fossU species, and the 10 ITpp(>r 

 Cretaceous species, like those of the genus 

 Paliurus, are confined to North America. Tli(>y 

 are found hi the Raritan and Magothy forma- 

 tions of New Jersey and Maryland, the Eutaw 

 formation of Georgia, the Tuscaloosa formation 

 of .Vlabama, tlie Woodbine sand of Texas, the 

 Dakota sandstone of the West, the Patoot 

 beds of Greenland, and the LTpper Cretaceous of 

 Alaska. Thert! are about 20 Eocene sj)eeies, 

 includmg tli(\ two common and characteristic 

 species of the Wilcox and 1 in the overly inc 

 (laiborne of the embayment region, 5 in the 

 Denver, 3 in the Fort Union, 2 in the Green 

 River, 1 in Alaska, and 1 in west Greenland. 

 There are 2 Paleocene sjx'cies in Franc(> and 

 Belgium, 4 Ypresian speci(>s in the south of 

 England, and a Lutetian species in Framn^ 

 Eight 01igoc(Mie species are very common in 

 ch>posits of this age thi-oughout Europe. More 

 than 20 species have been recorded from the 

 Miocene of Colorado and California in this 

 country, of France, Switzerland, Germany, 

 Italy, Austria-Hungary, and Russia in Europe, 

 and of Japan and Java in Asia. There are 3 

 or 4 Pliocene s[)ecies hi Europe. Though the 

 evidence is not so clear as for Paliurus, there 

 is a possibility that Zizy|)hus too is of occi- 

 dental orighi. 



The genus Reynosia Grisebacli, which con- 

 tains only 2 existing coastal species, ranging 

 from the Florida Keys through the AVest 

 Indies, includes 2 characteristic species based 

 on leav(!s in tlu! Wilcox flora and a third species 



