FLORA OF THE GREEN RIVER GROUP. 179 



MALVACEJE. 



STERCULIA, Linn. 



Schimper remarks, on the present distribution of this genus, that it 

 has made its appearance in Europe at the first stage of the Tertiary, as it is 

 already reported in the "Flora of Sezanne;" that it has had its largest rep- 

 resentation in the Miocene, and has since totally disappeared from the 

 continent. The numerous forms of leaves of this genus described in this 

 volume from the Dakota Group prove that the origin of these plants should 

 be removed to the Cretaceous for the American continent at least. The 

 genus is thence found in the divers stages of the Tertiary, but far less 

 frequently here than in Europe. 



Sterculia rigid a, sp. nov. 

 Plate XXXIV, Fig. 12. 



Leaf subcoriaceous, rigid, cuneate at base, tripalmately lobed; lobes cut to near 

 the base, narrowly lanceolate, sharply acuminate, very entire, the lateral shorter and 

 narrower; nervation obsolete. 



I have seen another leaf of the same character since the first was 

 figured, but it does not show anything more except the base, which is 

 cuneate, or like a continuation of fig. 12, to the top of the petiole. The 

 leaves are small, 5i centimeters between the points of the lateral lobes, 7 

 centimeters long from the base to the apex of the medial lobe which is 6 

 centimeters long, the lateral only four. The only species related to this 

 is S. Labrusca, common in the Miocene, but the relation is distant. 



Hah. — Florissant; very rare. Princeton Museum, No. 667. Lacoe's 

 Collection. No. 44. 



TILIACEvE. 



TILIA, Linn. 



Tilia populifolia, sp. nov. 



Plate XXXIV, Figs. 8, 9. 



Leaves large, round or subcordate at base, deltoid-acuminate to the apex, deeply 

 regularly serrate, palmately five-nerved ; upper lateral nerves somewhat thicker and 

 more distant, the secondary parallel, slightly curving, branchiDg near the borders. 

 Leaves large, variable in size. 



At first the leaf, fig. 8, seems to represent a Populus on account of the 



