52 CONTRIBUTIONS TO PAL^ONTOLOGY 



Dryophyllum bruneri Ward, U. S. Geol. Surv., 6th Ann. Rept., 551, pl. 36, figs. 6-9, 1886; idem, BuU. 37, 27, 



pl. 10, figs. 5-8, 1887; Knowlton, U. S. Geol. Surv. Prof. Paper 101, 259, pl. 53, fig. 5, 1917. 

 Dryophyllum Jalcalum Ward, U. S. Geol. Surv., 6th Ann. R«pt., 551, pl. 37, fig. 10, 1886; idem, BuU. 37, 27, 



pl. 11, fig. 1, 1887; KJiowlton, U. S. Geol. Surv. Bull. 163, 42, pl. 8, fig. 1, 1900. 

 Quercus gracilis Newberry, U. S. Nat. Mus. Proc, vol. 5, 504, 1883; U. S. Geol. Surv. Mon. 35, 75, pl. 67, 



fig. 4, 1898. 

 Quercus doljensis Pilar. Ward, U. S. Geol. Surv., 6th Ann. Rept., 551, pl. 36, figs. 9, 10, 1886; idem, Bull. 37, 



25, pl. 9, figs. 4, 5, 1887. 

 Quercus whitmani Knowlton, U. S. Geol. Surv. Prof. Paper 155, 52, pl. 17, fig. 5, 1930. 

 Quercus turhulenla HoUick, U. S. Geol. Surv. Prof. Paper 159, 70, pl. 38, fig. 3, 1930. 

 Rhus pseudo-meriani Lesquereux, Rept. U. S. Geol. Surv. Terr., vol. 7, 293, pl. 58, fig. 11, 1878. 

 Fraxinus? princetoniana Knowlton, U. S. Geol. Surv. Prof. Paper 130, 161, pl. 22, fig. 7, 1922. 



Thi.s type of leaf is recorded from 5 of the 6 Medicine Bow localities and is usually one of the 

 dominants. The large number of specimens collected for study were at first considered to repre- 

 sent 5 distinct species on the basis of identity with figured specimens. It was confusing, however, 

 to discover that there were intermediate types present with a few characteristics of one species 

 but the remaining characteristics of another species. After consulting the type collections at the 

 U. S. National Museum, it has seemed necessary to regard all of these species as variants of a 

 single rather well-defined leaf type. 



The original specimen of Dryophyllum {Quercus) subfalcatum was coUected from what is now 

 called the Mesaverde formation at Point of Rocks, Wyoming. In the following decade Ward 

 and Newberry independently described additional specimens of this same type of leaf from the 

 same locality, as Dryophyllum bruneri Ward and Quercus gracilis Newberry. Neitlier author 

 mentioned the work of the other nor made any reference to tlie similar leaf described by Lesque- 

 reux. Knowlton clarified this situation by synonymizing both species with Dryophyllum sub- 

 falcatum,^ although D. bruneri was inadvertently restored to its specific status in Bulletin 696. 



From the shghtly younger Black Buttes flora of the same region specimens of essentially 

 identical type were variously described as D. aquamarum Ward, Quercus doljensis Pilar, and Rhv^ 

 pseudo-meriana Lesquereux. In a recent synonymy Brown has included the first of these in 

 Dryophyllum subfalcatum.'^ I ani including the last two, already combined as one species by 

 Knowlton,^ as possessing no recognizable differences. Brown has also inchided, on justifiable 

 evidence, the specimens hitherto referred to Dryophyllum falcatum Ward, Querciis whitmani 

 Knowlton, and Q. turbulenta Hollick from scattered beds of late Cretaceous age. To these I 

 would add the specimen of Fraxinusf princetoniana from the Laramie flora. 



Among my specimens which I have collected from the lower Lance east of Lance Creek, 

 Wyoming, there are several specimens of Dryophyllum subfalcatum to add to the Lance occurrences 

 recorded by Knowlton ^ and Brown.^ Moreover, a single specimen of the same species was tenta- 

 tively described as Juglans? confusa by Knowlton in an unfinished manuscript on a collection 

 from the Lance formation of "Converse County," Wyoming. 



As now conceived by Dr. Brown and me, this is a valuable index species of the late Creta- 

 ceous, being well defined, widespread, and usually abundant. It is unfortunate that as good use 

 cannot be made of it in ecologic and climatic considerations owing to its uncertain botanical affinities. 

 Cretaceous leaves of tliis type are usually referred without further consideration to the genus 

 Dryophyllum, held to be prototypic of the family Fagacese. Tertiary specimens of the same 

 general character are ordinarily referred to Castanea or Quercus, though often on insufficient evi- 

 dence. I would hesitate, in the absence of seeds, to remove the present species to either Castanea 

 or Quercus, although the resemblance to many species of these genera is admittedly striking. 



Occurrence — Corson Ranch, Wyoming, Locs. P. 371, P. 372; north of Walcott, Wyoming, 

 Loc. P. 373; Elk Mountain road, Wyoming, Loc. P. 374; Craig, Colorado, Loc. P. 376. 



Collection—V. C. Mus. Pah, Plesiotypes Nos. 1313, 1314, 1315. 



> Knowlton, F. H., U. S. Geol. Surv. Bull. 163, 41, 1900; idem, BuU. 690, 246, 1919. 

 2 Brown, R. W., U. S. Geol. Surv. Prof. Paper, manuscript, 1937. 

 ' Knowlton, F. H., U. S. Geol. Surv. BuU. 696, 525, 1919. 

 ' Knowlton, F. H., Wash. Acad. Sci. Proc, vol. 11, 211, 1909. 

 ' Brown, R. W., op. cit. 



