THE FLORA OF THE SAINT EUGENE SILTS 



411 



eies by various authors.''* Certain of those forms are undoubt- 

 edly identical with the species as originally described and fig- 

 ured by Goeppert, but others are of doubtful identity, and none 

 is as large as ours. 



A species that is, perhaps, more closely similar to ours, both 

 in size and general appearance, is Platanus dissecta Lesque- 

 reux,^^ from the late Tertiary (probably Miocene) of the western 

 United States ; and the only apparent difference between them is 

 that ours are prevailingly larger in size and with a somewhat 

 more divergent or spreading character in connection with the 

 lateral lobes. 



Whatever may be thought of such surficial and minor differ- 

 ences as may be noted between the existing Platanus occiden- 

 talis and the three fossil forms P. pseudoccidentalis, P. acci- 

 oides, and P. dissecta, it is apparent that their resemblance to 

 each other is so close that in certain instances satisfactory dif- 

 ferentiation would be difficult, if not impossible, and hence it 

 would be hazardous to regard any specimen of the general type 

 of Platanus leaf to which they belong as a safe index fossil in 

 critical stratigraphie work. All that may be safely said in this 

 connection, as far as our specimens described and figured under 

 the name P. pseudoccidentalis are concerned, is that they are 

 more suggestive of certain Tertiary species than they are of any 

 Quaternary species thus far described or depicted. 



Incidentally, and for purposes of comparison, it may here be 

 pertinent to call attention to two fossil leaves from the Pleisto- 

 cene of the Don Valley, Toronto, Canada, that were described 

 and figured by Penhallow,^" under the names Acer pleistoceni- 



34Heer, Oswald, (a) Flora Tertiaria Helvetiae, vol. 2, pi. 87, figs. 3, 4; pi. 88, 

 figs. 8, 11, 12. 1856. (b) Flora fossilis aretica, vol. 1, pi. 32 (Spitzbergen) , figs. 

 1, 2. 1868. (c) Idem, vol. 4, No. 1 (Beitrage zur fossilen Flora Spitzbergeus), 

 pi. 17, figs. 1, 2; pi. 31, fig. 3. 1876. (d) Idem, vol. 7 (Greeuland), pi. 90. 1883. 



Berry, E. W. Fossil plants from the late Tertiary of Oklahoma. U. S. Natl. 

 Mus., Proe. vol. 54, pi. 94, fig. 3; pi. 95, fig. 5. 1918. 



33 Lesquereux, Leo. Eeport on the fossil plants of the auriferous gravel deposits 

 of the Sierra Nevada. Mus. Comp. Zool. Harvard Coll., Mem. vol. B, no. 2, p. 13, 

 pi. 7, fig. 12; pi. 10, figs. 4, 5. 1878. 



sspenhallow, D. P. (a) Geol. Soc. America, Bull. vol. 1, p. 327, text fig. 1. 

 Ap. 1890. (b) Amer. Naturalist, vol. 41, p. 443, text fig. 1 (reduced 0.55). 1907 

 {-Acer pleistooewicum) . Idem, p. 444, text fig. 2 (reduced 0.55) {-Acer toronto- 

 niense) . 



