MUSEUM OF COMPAEATIVE ZOOLOGY. 59 



conspicuous by the presence of some of the most common species of the 

 Miocene, even of some species still living at the present epoch, as seen 

 above, which had not been observed at anv of the localities of the 

 Eastern States where the specimens I had for my first examination 

 had been found. These species, Populus arctica, P. Nebrascensis, P. 

 crenata, Platanus Guillelmce, P. acei'oides, Aralia notatn or Platamis 

 nobilis, Tilia antiqua, Negundo decurrens, closely allied if not a mere 

 variety of Negundo triloba, Gary a antiquorum, Amelanchier typica, all 

 Miocene species, now found in the collection made at Golden, show an 

 intimate relation between the flora of Golden and that of Fort Union, 

 which by new discoveries will probably become more apparent between 

 the different localities of the Laramie Group, and complete the evidence 

 of tlie unity of the characters of the flora. 



The group of plants described here aff'ord a remarkable evidence of 

 the distribution of vegetable remains under peculiar circumstances. 

 The specimens w'ere obtained from a locality which has been visited 

 many times by members of the U. S. Geological Surveys of the Terri- 

 tories, often by Mr. Lakes himself, and twice by myself. Nevertheless, 

 not a single specimen of Populus Nebrascensis, nor of Platanus Guillelmce, 

 had been found there before ; yet in a locality at the same horizon and 

 at a very short distance, a few rods only, as far as I know, from the ex- 

 cavations formerly made, specimens of these two species and their varie- 

 ties have been obtained in such abundance that they constitute nearly 

 one half of the collection. This proves that the mode of distribution of 

 the vegetable remains results in some cases from the deposition of the 

 fragments at the place where the trees have grown, not from transporta- 

 tion by water. Though the specimens of Golden are very fragmentary, 

 they are generally flat upon the surface of shale apparently composed 

 of muddy deposits, seemingly pi-ogressing in their formation while the 

 leaves were falling from trees grown either around woody swamps or on 

 the borders of shallow lakes. 



Recent explorations have brought on the discovery of a large number 

 of localities rich in remains of fossil plants, over the whole extent of the 

 Great Lignitic. The flora of the Laramie Group, wliich now counts 

 only 250 species, will therefore probably soon become better known, and 

 by the greatly increased number of its species will take an important 

 place in the history of the ancient vegetation of the earth. 



