108 THE LATER EXTINCT FLORAS OF NORTH AMERICA. 



and the deviation from the common form is not so great in these fossils as 

 in the living species I have named, or the fossil species named by Unger, 

 P grandifolia and P. Sirii (Chlor. Prot, p. 136, PI. XLV, figs. 1-5, and 

 Foss. Fl. Sotzka, p. 36 [166], PL XV [XXXVI]), fig. 1. 



In size these leaves exceed those of any known species of Sycamore, 

 and if we are correct in referring them to Platanus, they may be considered 

 the only relics we have of by far the noblest species of the genus. Some 

 of the leaves are a foot and a half in length and of about equal breadth, 

 and yet they do not so far exceed the ordinary size of the leaves of the 

 Sycamores as do the leaves of Acer macrophyllum those of other species 

 of maple. 



Since the above notes were written, Lesquereux has described (Tert. 

 FL, p. 237, PL XXXIX, figs. 2-4) some trilobate, sometimes five-lobed 

 leaves, which he compares with Platanus nobilis, and is inclined to regard 

 them as identical; but it will only be necessary to refer to the figures 

 now given, especially that on Plate L, to show that the differences are 

 such as to distinctly separate them. In Aralia notata Lesq., the general 

 plan is not unlike that of the leaves in question (which is true also of most 

 trilobate leaves), but here the resemblance ceases, for in A. notata the mar- 

 gins are entire and the lateral nerves connect in festoons along the margin 

 (camptodrome), whereas in P. nobilis the lateral branches terminate in the 

 teeth with which the margins of the lobes are set (craspedodrome). 



In the Report of Progress of the Geological and Natural History 

 Survey of Canada for 1879-80, Appendix N, Prof. J. W. Dawson gives 

 notes on a number of species of plants collected on the Souris River, and 

 among others he mentions Platanus nobilis, of which good specimens were 

 procured by Dr. Selwyn and Dr. Gr. M. Dawson, and he confirms, by 

 observations on these specimens, my reference to the genus Platanus. He 

 also mentions a feature which does not appear in any of the specimens I 

 have seen, namely, two short basal lobes extending backward on the 

 petiole. This is not, however, unprecedented in the leaves of Platanus, as 

 I have seen something of the kind in the large leaves borne by 3^oung and 

 vigorous plants of P. occidentalis. The figure given on PL L is of the 

 natural size, and attests the magnitude claimed for some of the leaves of 

 this magnificent tree. When it is realized that the main nerves of the 

 middle and lateral lobes must unite at a point some inches below the part 



