THE FLORA. 



125 



Occurrence: Laramie forma tion,»cut on Mof- 

 fat railroad (Denver & Salt Lake) about 6 or 

 8 miles north of Golden, Colo., collected by 

 A. C. Peale, 1908. 



Salix wyomingensis Knowlton and Cockerell. 



Plate IV, figures 3, 4, 8. 



Salix unjommgensis Knowlton and Cockerell, U. S. Geol. 



Survey Bull. 696, p. 572, 1919. 

 Salix integra Goppert, Deutsch. geol. Gesell. Zeitschr., 

 vol. 4, p. 493, 1852. 

 Lesquereux, U. S. Geol. and Geog. Survey Terr. Ann. 

 Kept, for 1873, p. 397, 1874; Tertiary flora: U. S. 

 Geol. Survey Terr. Rept., vol. 7, p. 167, pi. 7, figs, 

 1, 2, 1878. 



The American specimens on which is based 

 the determination that this form occurs in the 

 United States are included in the collections of 

 the United States National Museum (No. 197) 

 and are preserved on the red baked shale char- 

 acteristic of a certain horizon at Black Buttes, 

 Wyo. They agree fairly well with the Euro- 

 pean figures of this species, and the species may 

 be considered as probably present in this 

 country. 



In the "Tertiary flora" Lesquereux mentions 

 a single example from Golden, Colo. This 

 specimen is No. 837 of the United States 

 National Museum collection and is preserved 

 on a hard fine-gramed whitish sandstone char- 

 acteristic of the Laramie at Golden. This spe- 

 cies is also represented by specimens from Coal 

 Creek, Boulder County, Colo., one of the best 

 preserved of which is shown in Plate IV, 

 figure 8. 



In a collection made at Marshall by Peale 

 there are a number of willow leaves, the most 

 perfect of which are here figured (PI. IV, figs. 

 3, 4). They are evidently fairly thick, but the 

 nervation is obscure. So far as can be made 

 out, however, they are the same as the form 

 figured by Lesquereux under the name Salix 

 integra. It is to be noted that the leaves of 

 SaJix are often lacking in diagnostic characters, 

 and they are described with difficulty. 



Occurrence: Laramie formation, Golden, 

 Colo., original collections studied by Lesque- 

 reux; Coal Creek, Boulder County, Colo., col- 

 lected by N. L. Britton about 1884; Marshall, 

 Colo., collected by A. C. Peale, 1908. Post- 

 Laramie (in my opinion). Black Buttes, Wyo. 

 85344—22 9 



Salix brittoniana Knowlton, n. sp. 



Plate XXI, figure 8. 



Salix brittoniana Knowlton [nomen nudum], U. S. Geol. 

 Survey Bull. 696, p. 565, 1919. 



Leaf of firm texture, narrowly lanceolate, 

 tapering below to a long, narrowly wedge- 

 shaped base; apex not preserved; margin 

 perfectly entire; nervation strong, pinnate, 

 consisting of a relatively strong midrib and 

 probably 8 or 10 pairs of alternate, remote 

 secondaries, each of which arises at an acute 

 angle, passes upward for a long distance, and 

 disappears near the margin or unites by a 

 slender apex to the secondary next above; 

 nervilles none; finer nervation obscure but 

 apparently consisting of a minute quadrangular 

 areolation. 



The type of this species, and unfortunately 

 the only one observed, lacks the upper portion 

 of the leaf and would not be described as new 

 except for the marked difference between it 

 and anything else thus far noted in these beds. 

 The portion observed, which includes the base, 

 is 5.5 centimeters long and was possibly twice 

 this length when perfect; the width does not 

 exceed 1 centimeter. Its principal feature is 

 the secondary nervation, described above. 



As regards size, shape, and margin this leaf 

 is very much like many leaves that have been 

 referred to Salix angusta Al. Braun,'" but it 

 differs distinctly in the nervation; so also it 

 agrees with S. amygdalaefolia Lesquereux as 

 regards the type of secondary nervation but 

 differs in shape and margin. It is believed to 

 be hardly worth while to foUow resemblances 

 further, as willow leaves are in general so 

 variable, yet it is thought that this species, 

 fragmentary as the type is, is sufficiently well 

 marked to be readily recognized in the future. 

 It has been named in honor of N. L. Britton, 

 director of the New York Botanical Garden, 

 who collected it. 



Occuri-ence : Laramie formation. Coal Creek, 

 Boulder County, Colo. (Laramie), collected by 

 N. L. Britton about 1880. 



'» Of. Lesquereux, Leo, The Tertiary flora: U. S. Geol. Survey Terr. 

 Kept., vol. 7, pi. 22, flg. 4, 1878. 



