Relict Miocene flora. 175 
Miocene Living 
Populus balsamoides Goepp. Populus balsamifera L. 
Platanus aceroides Goepp. Platanus occidentalis L. 
Juglans bilinica Unger \ 
»  longifolia Heer J einer 
Vitis teutonica A. Br. Vitis vulpina L. 
Tilia Malmgreni Heer Tilia americana L. 
Liquidambar europaeum A. Br. \ A i 
5 protensum Unger f Liquidambar styraciflua L. 
Magnolia primigenia Unger Magnolia grandiflora L. 
Liriodendron Procaccinii Unger‘) Liriodendron tulipifera L. 
Sassafras Aesculapi Heer Sassafras officinalis Nees. 
Taxodium distichum L. Taxodium distichum L. 
Sequoia Langsdorfii A. Br. Sequoia sempervirens Endl. 
> Sternbergii Goepp. »  gigantea Lindl. 
The climate of the Eocene and Miocene periods was milder than at present 
and over much of North America was somewhat sub-tropic in character. This 
warm zone extended well into the Arctic regions and a temperature compar- 
able to that of southern New England, or New Jersey existed in far northern 
latitudes. It is not to be wondered at that we find preserved as relicts of a 
lower Miocene flora (upper eocene of Lesquereux *) such subtropic genera, as 
Carya, Cassia, Cinnamomum, Cissus, Ficus, Laurus, Morus, Persea, Personta, 
and Rhus and that a large number of palm species of the genus Sabal occur 
on the upper Missouri. The abundant brown coal layers of Grinnell Land’) 
81° 46’ north latitude reveal a flora of birches, poplars, elms, lindens, hazel- 
nuts, 7, axodium, Picea excelsa, and pines similar in constitution to that which 
we find at the present in 50° to 60° north latitude, except that the northern 
limit of Tarodium at present is about 39° north latitude. To find a similar 
tropic flora today, we must visit 15° or 25° north latitude, where we enter a 
region in which grow many species of Carya, Cassia, Ficus and genera of 
the natural order Lauraceae. The species of Sadal and Chamaerops (Rhapido- 
Phyllum!) occur in South Carolina and Florida. 
If it is not possible to arrange all of the fossil genera and species with 
Teference to their past distribution, it is possible to positively assert, that in 
Northwest America during the younger Tertiary, or Neogene (comprising the 
Miocene and Pliocene) occurred such living genera, as Betula, Diospyros, 
nn 
1) Considerable doubt has been thrown on these fossil species of tulip tree because all of 
the fossil leaf forms have been duplicated from living trees. See in this connection. — HoLm: 
Otes on the leaves of Liriodendron. Proceedings National Museum, XIII, pp. 1535. 1890. 
plates IY_ıx. 
2) LesQuerevx, L.: American Jonrnal Science and Arts. 1374: 399. 
3) Heer, O.: Flora fossilis arctica V. 1878. 
