FLORA OF THE GREEN RIVER GROUP. 159 



Populus oxyphylla, Sap. 

 Plate XXXVIII, Figs. 9-11. 

 Sap., "fit ," iii, 1, p. 73, pi. vii, fig. 1. 



Leaves of small size, loug petiolate, deltoid, shortacuuiiuate, rounded to the 

 base, denticulate; secondary nerves variable in distance, the lower longer, branching 

 outside. 



The leaves vary from 2h to 4 centimeters long and from li to 2^ 

 centimeters broad belo^v the middle, from which part they taper upward 

 to a point or short acmnen; the petiole is 2 to 3 centimeters long. The 

 author describes and figures the lateral nerves as flexuous, a character 

 which is not seen on the leaves which I refer to this species. The nerves 

 are, however, camptodrome, the teeth being entered, as seen in fig. 11, 

 the best preserved leaf, by short veinlets anastomosing to the curves of 

 the lateral nerves. In this leaf also the nervilles and their mode of rami- 

 fication in forming large primary irregularly hexagonal meshes are of the 

 same type as in the figure of Saporta. 



ir«5.— Florissant. U. S. Geol. Expl. Dr. F. V. Hoyden. One speci- 

 men. No. 54. not figured here, is in the collection of Mr. Lacoe. 



Populus Ricliartlsoni, Heer. 



" U. S. Geol. Rep.," vii, p. 177, pi. xxii, figs. 10-12. 



Populus arctica, Heer. 

 Ibid., p. 178, pi. xxiii, figs. 1-6. 



BALSAMIFLUiE. 



LiaUIDAMBAR, Linn. 



Ibid... vii, p. 186. 



Liiquidambar Europseum, Al. Br. 



Plate XXXII, Fig. 1. 



Al Braun, "Buckl. Geol ," p. 112; Ung., '-Chlor. Protog.," p. 120, pi. xxx, figs. 1-5; Goepp., '^'ert. Fl. v. 

 Schoss.," p. 22, pi. xii, figs. 6,7; Heer, "Fl. Tert. Helv.," ii, p. 6, pi. li, Iii, figs. 1-8; Ludw., 

 " PaliEontog.," viii, p. 89, pi. xxv, figs. 1-4 ; Gaiul., "Contrib.," iv, p. 19, pi. iv, figs. 5-7. 



Leaves long-petioled, palmately 3 to5-lobed; lobes more or less distinctly glaudu- 

 lose, serrulate, lanceolate-acuminate. 



In the leaf figured as referable to this species the borders appear 

 nearly entire or merely undulate-crenate ; but it is the only difference 

 from the normal form which is very common in the Miocene of Europe. 



