THE FLORA. 



141 



This fine species, which appears to be quite 

 unlike anything before reported from the 

 Laramie, is represented by the nearly perfect 

 example figured and by another, much poorer 

 specimen which has little but the margin pre- 

 served. The form is broadly reniform, entire 

 leaf about 6.5 centimeters wide and about 5.5 

 centimeters long, exclusive of the petiole, which 

 is 17 millimeters along and 2 millimeters in 

 diameter. The leaf is characterized by the 

 three strong palmate ribs, the central with 

 three or four camptodrome secondaries, and the 

 lateral with an equal number of tertiary 

 branches, all the ultimate branches of second- 

 aries and tertiaries anastomosing, and with one 

 or two series of broad loops outside. 



After a somewhat careful comparison of this 

 species with both living and fossil leaves re- 

 ferred to the genus Aristolochia, there can be 

 little doubt as to the correctness of this deter- 

 mination. Among the living species, for ex- 

 ample, it has very much the same shape as 

 A. clematis Linne" and A. hirta Linn6, both of 

 the Old World, and in both form and nervation 

 it approaches the American A. tomentosa Sims. 



Among the fossil species described, the one 

 under discussion somewhat resembles A. aes- 

 culapi Heer, 5 but is a little larger. It is also 

 considerably like A. cordifolia Newberry, 6 

 from the Fort Union formation of Montana, 

 which differs in being longer than broad and 

 in having five ribs springing from the top of 

 the petiole. 



Among the specimens from Marshall's mine 

 is a fragment of the upper portion of a leaf 

 that is referred with some hesitation to this 

 species. It was a somewhat larger leaf, with 

 a slightly more obtuse apex and a relatively 

 thicker midrib. It bears about four pairs of 

 alternate or subopposite, remote secondaries, 

 which arch by a broad curve far within the 

 margin and are provided with two or three 

 distinct series of large loops outside. There 

 are also intermediate secondaries which anasto- 

 mose with the main secondaries by irregular 

 rectangular areas. This is certainly a leaf of 

 the same type as that first described and hardly 

 differs, except as regards the intermediate sec- 



5 Heer, Oswald, Flora tertiaria Helvetiae, vol. 2, p. 104, pi. C. flg. 11, 

 1856. 

 » Newberry, J. S., U. S. Geol. Survey Mon. 35, pi. 40, flg. 7, 1898. 



ondaries and the more irregular nervilles. It 

 may be a different but closely related species, 

 but it seems best, in the light of our present 

 knowledge, to regard them as identical. 



This, species is named in honor of Dr. N. L. 

 Britton, director of the New York Botanical 

 Garden, by whom the specimens were collected. 



Occurrence: Laramie formation, Coal Creek 

 and Marshall's mine, Boulder County, Colo., 

 collected by N. L. Britton about 1880. 



Order RANALES. 



Family NYMPHAEACEAE. 



Nelumbo tenuifolia (Lesquereux) Knowlton. 



Plate XXVI, figure 7. 



Nelumbo tenuifolia (Lesquereux) Knowlton, U. S. Geol. 



Survey Bull. 696, p. 407, 1919. 

 Nelumbium tenuifolium Lesquereux, U. S. Geol. and 

 Geog. Survey Terr. Ann. Rept. for 1873, pp. 382, 

 402, 1874; idem for 1876, p. 514, 1878; Tertiary 

 flora: U. S. Geol. Survey Terr. Rept., vol. 7, p. 

 253, pi. 46, fig. 3, 1878. 



The type specimen of this species is pre- 

 served in the United States National Museum 

 (No. 372, by error in the catalogue, 472). It 

 is very indistinct, and the figure of it in the 

 "Tertiary flora" is far from accurate. The 

 only part of the true margin preserved is a 

 fragment hardly 3 centimeters in extent shown 

 in the upper left-hand portion of the figure. 

 A careful examination of the specimen fails to 

 show the margin in the lower portion, as given 

 in the figure. This proves that the leaf was 

 larger than appears from the drawing. It has 

 thin ribs, as described by Lesquereux, and the 

 whole leaf appears to have been of thin texture. 

 In the original description Lesquereux states 

 that the leaf is "exactly round, peltate from 

 the middle, and 8 or 9 centimeters in diameter." 

 As noted above, the type specimen is larger 

 than the description calls for, being fully 10 

 centimeters in diameter. The ribs are 13 in 

 number, but this feature is of little or no 

 specific significance. 



This species is most closely related to 

 Nelumbo lakesiana (Lesquereux) Knowlton, 7 

 a well-known Denver species, from which it 

 differs in its obviously thin texture, thin ribs, 

 and smooth surface. 



i Lesquereux, Leo, The Tertiary flora: U. S. Geol. Survey Terr. Rept., 

 vol. 7, p. 252, pi. 46, figs. 1, 2, 1878. 



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