336 UNITED STATES GEOLOGICAL SDRVEY— TERTIARY FLORA. 



pean Miocene species, Arundo Gaiqierti, Quercus Haydingeri, Populus Zo.d- 

 dachi, Ficus multinervis, and, as related types of the same age peculiar to 

 this group, we have Equisetum Wyomingense, Arundo reperta, Ficus arenacea, 

 and Eucalyptus Americana, plants whose affinity seems with more recent 

 vegetable types than those of the Miocene. Two species of Myrica, M. 

 nigricans and M. Bolanderi, are related to congeners of the upper divisions, 

 while Ilex affinis, and Arnpelopsis tertiaria, which is closely related to, even 

 perhaps identical with the \Wu\g A. quinquefoUa, relate this group to the pres- 

 ent flora. Its affinities are evidently with less ancient types than those of 

 the third group. 



But still the Upper Green River division seems to have a more recent 

 character. With the first group, it has in common only Sequoia Langsdorjfii, 

 Acorus hraclujstachys, and a Podogonium, all Upper Miocene. Juglans ther- 

 malis, found in lava deposits, is of doubtful reference for the station. With 

 the second, it has Taxodium distichum, Acorus hrachystachys, Alnus Kcfersteinii, 

 and Acer trilobatum, all species not merely Miocene, but, as seen from our 

 table, of a very wide and general distribution ; and, independently of its rela- 

 tion to the other divisions, the flora of this group has Glyptostrohus Europeus, 

 Pinus palceostrobus, Myrica acumiriata, M. undulata, M. Ludwigii, M. latiloha, 

 Carpinus grandis, Fagus feronice, Quercus drymeja, Castanea intermedia, Sallx 

 elongata, Populus Richardsoni, Planera TJngeri, Ficus Jynx, Fraxinus pradicta, 

 Vaccinium nticulaium, a\\ of the European Upper Miocene; and, as closely 

 allied to plants of the same age by their types, two species of Salvinia, Se- 

 quoia angustifolia and Pterocarya Americana. The Pliocene flora of California, 

 known now by the species of the Gold-bearing Gravel of Nevada County, 

 and of some other localities, especially of Oregon, oflTers us also a jioint of 

 comparison Ijy two identical species, Uhnus tenuinervis and Acer (equidenta- 

 tum, while with plants of the jjresent time the relation is marked hy Hi/pnum 

 Haydenii, Equisetum limosum, and the fine Staphy/ea acuminata. All this 

 evidently weakens in this flora the Miocene facias, so distinct in that of the 

 third group. Indeed, taken altogether, both divisions of the fourth group 

 might be ascribed to the Lower Pliocene; four of their species being, as far 

 as it can be ascertained from the characters of the leaves, identical with plants 

 of our time. The relation to the European Miocene is, however, still too 

 close, while it is too distant from the Pliocene flora represented by the spe- 

 cies of the Gold Gravel of Calil'ornia. 



