810 The American Naturalist, [September, 
III. Species originating in the Eocene.—P. aceroides, gul- 
telme, haydenu, raynoldsii, and rhomboidea, 
. IV. Species not occurring below the Miocene.—P. aceroides 
academie and aceroides dissecta. 
It will be observed that in the above distribution I have not 
considered the Fort Union group, the Denver formation, nor any 
of the deposits along the Union Pacific Railroad, except those on 
Bitter Creek, to be Cretaceous. I have also excluded the Boze- 
man coal mines containing P. aceroides. The radical difference 
between this distribution and that of Professor Jankó renders 
needless any discussion of his argument from geological consid- 
erations; and although I believe an argument can be based on 
these considerations, it would require to take into the account the 
more abnormal and archaic forms which he excludes from the 
genus. This argument is already stated in my previous papers, 
and the present one has become too long to admit of its expan- 
sion here, | 
EXPLANATION OF PLATE XXVIII. 
Fic. 1.—Leaf of Platanus orientalis L., from Washington, D.C. (cult.). 
Fic. 2.—Lower portion of a leaf of Platanus occidentalis L., showing 
basilar and stipular appendages, from the District of Columbia. 
Fic. 3.—Leaf of Platanus racemosa Nutt., from California, collected by 
` Mrs. Austin. ; 
Fic. 4.— Sassafras ‚eretaceum Newb., Lesquereux, Cretaceous Flora, 
Pl. xr, Fig. t. Dakota group. 
