192 UNITED STATEa GEOLOGICAL SURVEY— TERTIARY FLORA. 



Ficus leaves merely rest upon more or less evident probabilities, as the largest 

 number of the fossil leaves referred to this genus could be ascribed to others 

 by the same reasons which induced the authors to admit them as Ficus. 

 And it is probable that the number of nearly one hundred fossil species now 

 described will be considerably reduced when they have been thoroughly 

 studied." In this memoir, tlie reference of the tertiary leaves to Ficus is 

 essentially based upon their identity, or close relation of characters, to spe- 

 cies described by European authors, who have access for their comparison 

 to large collections from the whole world, while I have at my disposal 

 only specimens from Cuba, Florida, and South America, which, though ref- 

 erable to numerous species, do not represent, by far, all the types of leaves 

 pertaining to this genus. 



The species of Ficus are extensively distributed between the tropics, 

 in the humid and warm regions of the equator especially. Many are found 

 in the West Indian Islands, in Jamaica and Cuba; three are indigenous in 

 Florida. A single one inhabits the southern regions of Europe. 



-As far as evidence can be credited, the origin of the genus is Creta- 

 ceous both in Europe and America. Prof. Heer has two species from 

 Moletin, one from Greenland, and one from the Dakota group. Three others 

 are described from this same formation in Dr. F. V. Hayden's Annual Re- 

 port, 1874, pp. 341 and 342, and four from Niedershoena by d'Ettingshausen. 

 From the Eocene floras of both continents, numerous leaves are referred to 

 Ficus, and the number greatly increases in Europe with the Miocene forma- 

 tion. In the Lignitic of the Rocky Mountains, Ficus leaves are most abundant 

 in connection with remains of Palms in the Lower Eocene of Black Buttes, 

 Golden, and the Raton Mountains; they are thus typical evidence of the 

 temperature of the epoch. 



§ I. — Penninerved leaves. 



Ficus lanccolata, Heer. 

 Plate XXVIII, Figs. 1-5. 



Fimis lanccolata, Heer, FI. Tert. Helv., ii, p. 62, pi. Ixsxi, figs. 2-5; iii, p. 182, pi. cli, figs. 34, 35; clii, 



fig. 13.— Mass., Fl. Senog., p. 223, pi. xxs, fig. «.— Ett.,Fl. Fofs. v. Bit., p. 67, pi. xx, figs. 



3, 4.— Heer, Mioc. Bait. Fl., p. 73, pi. xxii, tigs. 1, 2. — Sisoi., Mater., pi. xv, fig. 5 ; xxvi, 



fig. 2.— Lesqx., Anniial Report, 1671, p. 300; 1873, p. 414. 



Leaves coriaceous or subcoriaceous, entire, lanceolate, tapering upward to a long acnnien, and 



narrowed downward to a thick short petiole; midrib strong; lateral veins irregular in distance, camp- 



todrome. 



The leaves of this species are generally larger than those which are fig- 



