DESCRIPTION OP SPECIES— PLATANE^. 183 



Oeningen, Lohsau, Aix, etc., to find in Europe the first remains of Platanus, — 

 P. aceroides, Heer, and P. GuiUelmm, Goepp., two species so much alike that 

 they have for a long time been considered as one. In the Upper Lignitic 

 of the Rocky Mountains, we have the same two species in Alaska and at 

 Carbon; and still higher, in the Pliocene of California, there are two more, 

 P. appendiculata, Lesqx., which, like P. lindeniana, has bifid deciduous stipules, 

 and P. dissecta, Lesqx., whose leaves, sometimes tliree-lobate and less deeply 

 dentate, have a relation to P. r-acejnosa. P. aceroides being recognjzed as 

 ancestor of P. occidentalis, we find thus in the geological times forms inti- 

 mately related to those of the present flora of this continent, and therefore 

 a clear historical record of the genus. 



Platanus Guillelnise, Goepp 



PMe XXV, Figs. 1,2,3. 



Platanus GuiUelnun, Goepp., Foss. Fl. v. Schoss., p. 21, pi. xi, figs. 1,2. — Heer, Fl. Fobs. Arct., ii, p. 473, 

 pi. xlvii, xlviii, xlix, figs. 4 b, c, d. — Lesqx., Annual Report, 1871, pp. 289, 290 ; Supplement, p. 

 9 ; Annu.al Report, 1872, p. 387.* 



Platanus CEninghausiana, Goepp., loc. cit., pi. x, fig. 4. 



Platanus ateroides, Heer, Fl. Tert. Helv., ii, p. 71, pi. ixxxviii, figs. 13, 14 ; F). Foss. Arct., i, pi. xii. 



Leaves membranaceous, subtrilobate, with dentate or undulate borders, subtruncite or rapidly 

 narrowed to a short petiole. 



This form has been a long time considered by Heer as a mere variety 

 of P. aceroides, Goepp., and is still admitted as such by d'Ettingshaueen. Our 

 leaves, as figured in pi. xxv, do not show a clear distinction of the characters 

 which ought to separate the species. As far as our specimens indicate it, it 

 is scarcely possible to admit that they represent two specific forms. Figs. 4 

 and 5, which I think referable to P. aceroides, have the sharp and large teeth 

 of this species; but fig. 4 has the leaves more distinctly cuneate or narrowed 

 to the petiole, and fig. 5 has not any lobes, and these two characters refer 

 them to P. GuiUelmie. In the large number of specimens obtained of this 

 type at Carbon, some fragments have still longer, more acute lobes and teeth 

 than these two leaves, and therefore are more positively referable to P. 

 aceroides. In the three leaves which represent P. Guillelmce, fig. 3 has the 

 teeth scarcely marked, indeed, like mere undulations; in fig. 2, they are shorter 

 than in fig. 4, but already turned upward, and a slight increase of size and 

 sharpness of teeth and lobes does not seem to be of account for a specific 



* The specimens referred to this species from Placiferc.Kew Mexico, are too obscure for precise 

 determination. That of Black IJuttes, described in Report, 1872, is referable to Viburnum platanoides. 



