74(3 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



Platanus nobilis Newby.; I should not hesitate to consider it as identical, but 

 for the character of the lateral nerves, which are described by the author as 

 straight, and terminating' in the teeth of the margin. In this species the 

 borders are entire and the lateral nerves camptodrome. The difference may 

 be merely casual, for one of the specimens from Troublesome Creek has 

 the close secondary veins camptodrome along the borders of the inner side 

 of the lobes, while on the outer side the borders are obscurely cut by a 

 few small teeth, into which the veins enter as craspedodrome. Other speci- 

 mens, thus of Elk and Yellow creeks, 1 have the characters of P. nobilis." 



It would thus appear that Lesquereux himself inclined to regard the 

 Park specimens as being referable to Platanus nobilis, but in the 50 or more 

 specimens that I have studied from this place I have not found one showing 

 the teeth and craspedodrome nervation of P. nobilis. They all have the 

 distinctly camptodrome nerves, as shown in Lesquereux's figures. I have 

 therefore decided to keep them under Aralia. 



The further question of the correctness of this generic reference, or 

 rather of the relation of this Aralia notata to the genus Platanus, will not 

 now betaken up. Janko has said 2 that Platanus nobilis "non est Platanus," 

 while on the other hand Professor Ward has suggested 3 that several of the 

 so-called species of Aralia may have to be united into a group, under the 

 name of Protoplatanus, representing the ancestors of Platanus. A small 

 specimen of this species, obtained by Prof. J. P. hidings from a gulch north- 

 east of the peak west of Dunraven, is exceptionally well preserved, at least 

 as regards the finer nervation. This is A'ery regularly square, being only 

 about 0.25 mm. in size. The leaf appears to have been rather thick, possibly 

 coriaceous. 



No other specimen that I have seen has this finer nervation so well 

 preserved. 



Habitat: Fossil Forest Ridge, Yellowstone National Park,- bed No. 

 7, "Castanea bed", about 25 specimens; collected by Lester F. Ward 

 and F. H. Knowlton, August 16-20, 1887. Southeast end of hill above 

 (north) Lost Creek, bed No. 4, 2 leaves; collected by F. H. Knowlton, 

 August 8, 1888. Yellowstone River, one-half mile below mouth of Elk 



i Probably Elk Creek on Yellowstone River. F. H. K. 

 -Abstammung it. Platauen, Englers but. Jabrb., Vol. XI, 18S9, p. 456. 

 Types of the Laramie Fl., p. 63. 



