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EVIDENCE OF AGE OF LIGNITIC GROUP.

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tance; and, indeed, the Vancouver flora may show, in its details, markedpoints of dissimilarity to that of the Mississippi . But, one of the prom-inent characters of the Lower Lignitic is the predominance of Balms,and we find it manifest in all the localities named above. Indeed, I havefound remains of Palm, especially of Sabal, whenever I have seen LowerLiguite beds; aud, as it has been remarked formerly, Sabal Grayana hasbeen observed on specimens from Vancouver , Point of Bocks, Golden, theMississippi , &c. With this there are, in all these floras, a predominanceof subtropical forms, and the absence of northern types, rendering moreevident their correlation in time. Sufficient details have been given onthe species of the group, and on their distribution, in Dr. Hayden’sformer report (1873), p. 378 to 390.

The group of plants of the Evanston division has, as yet, no remainsof palm-leaves, but fruits doubtfully referable to the Palm family;with this it has some of its species of leaves represented at Golden,others at Carbon . The general character of its flora does not indicateas high an a verage degree of temperature as that of the Lower Lignitic.The group has been separated, as an intermediate one whose relation isnot positively fixed now. According to Professor Cope’s description,bones of Eocene vertebrate animals have been found in connection withit. Its true horizon may be rendered moredefinite by further discoveries.But in the group of Carbon the general character of the flora is evident,and its relation to the Miocene of Europe and of Greenland is exposed,not only by this general kind of related facies, but also by a number ofspecies, like Platanus aceroides and Guillelmw,* Acer, Populus arctica,Taxodium dubium, Alnus Kefersteinii Betula, Quercus , Corylus , indicating,together with the total absence of Palms, a marked difference in theclimatic circumstances governing the flora and that of the LowerLignitic group. This difference, also, is not remarked at Carbon only.It is reproduced in the same degree, by general affinity and identity ofspecies, in the flora of Coral-Hollow, San Joachin County, and of Con­ tra Costa , south of Mount Diablo, California ; of Bridge Creek, JohnDay Valley, and of Blue Mountain, Oregon ; of Bellingham Bay,ofAlaska , as established by Heer’s flora of that country, and therefore fol-lowed northward from Carbon to Greenland . Some of its types are sodefinite that a single specimen of a species of Acer or Platanus wouldsuffice to positively identify this group as Miocene , just as a few spec-imens of Quercus furcinervis proved the Eocene age of the Cascade Mount­ ains of Oregon , whose formations were at first supposed to be Post- Tertiary or of recent origin.

A few words more will be sufficient to answer the other objectionsrecorded at the beginning of this paper against the value of vegetablepaleontology in its application to geology for the determination of theage of the formations. We know now well enough that remains offossil plants are abundantly found in the land deposits of this continent.The result obtained from the onset of American researches in vegetablepaleontology let us surmise what an immense amount of documentarydata the after-coming geologist shall be able to gather in the samefield. The authority of animal-remains shall continue undoubted as faras it refers to marine formations. But when land formations are to beconsidered, theauthority should, when evident, be accepted as decisive.

' The fragment of leaf found in connection with the bones of the Saurian at BlackButte, and considered, from the character of nervation of the middle of the leaf, the only partpreserved, as doubtfully referable toP. Guillelmte ? was identified from better specimens,showing the outlines of whole leaves, as a new species of Viburnum, described in this paper asVibumun platanoides.