100 



LOWER EOCENE FLORAS OF SOUTHEASTERN NORTH AMERICA. 



confiucd to jVfrica, 1 {jcnus containing 12 

 sjK'cios that rango from Malaysia to Australia, 

 and 9 genera and lol species confined to 

 America. The remaining trilie, the Banis- 

 terie:v, includes a monoty]>ic genus in Asia, 

 2 genera and 15 s])(>ci('s in Africa, a single 

 genus and 7 species ranging from the East 

 Indies to Austraha, and 11 genera and 247 

 species confined to America. 



There are 21 monotypic g(>nera, distributed 

 as follows: Microsteira, confined to Madagas- 

 car: Flabellaria, confined to Africa; Caucan- 

 tluis, confined to Arabia; Brachylophon, con- 

 fined to Farther India; Mozia, Diplopteris, 

 Lophopteris, Clonodia, Coleostachys, Blcpha- 

 randra. Lophanthera, Verrucalaria, Pterandra, 

 Acmanthera, Diacicha, and Cdan^lonia, confined 

 to Brazil, Guiana, and Venezuela: Henleophy- 

 tum, confined to Cuba; Lasiocarpus and Eclii- 

 nopteris, confined to Mexico: and Tricomaria 

 and Mionandra, confined to Ai-gentina. 



Monotypic genera in general are suscep- 

 tible of two interpretations. They represent 

 either the last smwivors of a long line, as the 

 Ginkgo and Sassafras, or relatively recent 

 specializations. Of the foregoing monotypic 

 genera it seems probable that most are the 

 result of relatively recent evolution, since there 

 is nothing in then character or distribution to 

 suggest any extended geologic lustory and none 

 have been found in fossil floras. 



The fossil record is most incomplete. No 

 forms are known from the Upper Cretaceous, 

 though Ettingshausen recorded a species of 

 Malpighiastrum and one of BanisteriophyUmn 

 from the Upper Cretaceous of Australia. 

 Those identifications, however, are open to 

 the most serious question, and I do not con- 

 sider them of any weight in the discussion. 

 The family is certainly represent(>d in the 

 lower Eocene by 5 species of Malpighiastrum, 

 Hinea, and Banistcria in the Ypresian of the 

 south of England and by 5 species of Iiir;i'a 

 and Banisteria in the Wilcox flora, l)ased on 

 both leaves and characteristic fruits. There 

 are also doubtful species of Malpighiastrum 

 and BanisteriophyUum, described from the 

 Tertiary of Australia by Ettingshausen. Thus 

 there is no direct geologic evidence of the 

 ])l;ice of origin of the family. As the family 

 is so predominantly American at present, 

 and as only 2 genera have reached Australia 

 from the East Indian region, and as 2 of the 



American g(>nera appear in the northward 

 extension of the early Eocene flora of the 

 American Trojiics tkning the ATilcox epoch, 

 and are as ancient as any certain records of 

 the family anywhere, the conclusion is ex- 

 tremely pro])a])le that the family origmated 

 in equatorial America. With the exception 

 of the Wilcox records enmueratcd al)ove 

 nearly all the fossil records relate to Europe 

 and may be liriefly enumerated. 



The genus Malpighiastrmn Uuger con- 

 tains al)out 30 recorded species, including the 

 doubtful Upper Cretaceous and Tertiary spe- 

 cies previously mentioned as recorded by 

 Ettingshausen from eastern Australia; 3 

 Ypresian species from the south of England; 

 8 Oligocene species in France, Italy, Dalniatia, 

 StjTia, and Transylvania: aV)out 15 Miocene 

 species in Itah*, Prussia, Bohemia, Croatia, and 

 Transylvania, and 2 Pliocene species in Ital3^ 



The genus Heteropteris Jussieu, wliich in- 

 cludes about 90 existing species, ranging from 

 Mexico and the Antilles to Bolivia and Brazil, 

 includes a late Oligocene species in Transyl- 

 vania and 2 Miocene species in Styria and 

 Croatia. 



The genus Hirsea Jacquin, wliich contains 

 about 25 existing species ranguig from Mexico 

 and the Antilles to Peru, is represented by 

 about 10 fossil species, based for the most part 

 on the winged fruits. There is a species in the 

 Ypresian of southern England and a charac- 

 teristic fruit in the Wilcox ; 4 Oligocene species 

 in the Tyrol, St;\Tia, and Transylvania; 3 Mi- 

 ocene species in Baden, Styria, and Transyl- 

 vania; a Pliocene species in Brazil; and an 

 early Tertiary species in Ecuador. 



The genus Tetrapteris CavanUles, wliich in- 

 cludes about 60 existing species, ranging from 

 the West Indies and Mexico to southern Brazil 

 and Bolivia, contains a fossil species in the 

 Oligocene of Styi'ia and 3 Miocene species in 

 Bohemia, Styria, and Ci'oatia. 



The genus Stigmatophyllon Jussieu, which 

 comprises about 45 existing species in tht^ 

 Bahamas and Antilles and along the east coast 

 of America from Mexico to Uruguay, includes 

 a somewhat doubtfid form, identified by 

 Saporta, from the up])er Oligocene of France. 

 Similarly the genus Byrsonima L. C. Richard, 

 whose 90 existing species range frdin the 

 Bahamas and Mexico to southern Brazil and 

 Bolivia, has been recorded by Massalongo from 



