DESCRIPTIONS OF SPECIES. 105 



American sycamores, to the former of which it has considerable likeness 

 and may very well have been its progenitor. 



The fine leaf figured on PL XXXVIII, from La Bontes Creek, is 

 probably a young or abnormal state of this species, as it occurs with the 

 ordinary trilobate form 



Formation and locality: Tertiary (Eocene ?). Banks of the Yellow- 

 stone River, Montana. 



Plat anus latiloba Newb. 



PL I, fig. 4. 



Ann. N. Y. Lye. Nat. Hist., Vol. IX (April, 1868), p. 23; Ills. Cret. and Tert. PL 



(1878), PL II, fig. 4. 

 Platanus obtusiioba Lesq. Am. Jonrn. Sci., Vol. XL VI (July, 1868), p. 97. 

 Sassafras (Araliopsis) mirabile Lesq. ? Cret. Fl. (1874), p. 80, PI. XII, fig. 1. 



"Leaves petiolate, three-lobed, decurrent at the base, lobes broad, 

 obtuse, or abruptly acuminate; principal nerves three, secondary nerves 

 issuing from these at an acute angle, tertiary nerves leaving the secondary 

 at a right angle, forming a network over the surface of the leaf, of which 

 the areolae are subquadrate." 



Collected by Dr. F. V. Hayden. 



Judging from the imperfect specimens which we have of this species, it 

 is quite distinct from any described. Having the general form and nervation 

 of the leaves of P. occidentalism the margins are much less deeply sinuate, 

 the lobes less acuminate, and the entire outline of the leaf more simple. The 

 same is true of its relations with P. orientalis of the Old World. The fossil 

 species, of which several have been described by Unger and Groeppert, are 

 quite distinct from this. The species described by Unger (P. Sirii and P. 

 grandifolia) are much more deeply lobed, while that figured by Heer, 

 Goeppert, and Ettingshausen (P. aceroides) is less deeply lobed, but more 

 strongly toothed. All fossil species heretofore known are from the Tertiary 

 strata, this being the first instance where the genus has been found in rocks 

 of the Cretaceous epoch. 



A large number of nearly complete specimens of the leaf described 

 above have recently been obtained from the Dakota sandstones near 

 Fort Harker, Kansas. Some of these have come into the possession of 

 Lesquereux, who has included them in the genus Sassafras, and has figured 



