THE FLOKA. 



155 



There are several other leaves that have the 

 same shape and nervation as those described 

 above but are considerably larger. They are 

 referred to R. salicifolius, though they may rep- 

 resent a closely related form. 



Occurrence: Laramie formation, Marshall, 

 Boulder Coun,ty, Colo, (type) ; .Cowan station, 10 

 miles south of Denver, Colo., collected by F. H. 

 Knowlton; cut on Moffat railroad (Denver & 

 Salt Lake), collected by A. C. Peale, 1908. 

 Dawson arkose, Templeton Gap, 4 miles north- 

 east of Colorado Springs, Colo., collected by 

 A. C. Peale, 1908. Vermejo formation, Canon 

 City field (Rockvale), Colo., collected by George 

 Hadden; 2 miles west of Trinidad, Colo., col- 

 lected by G. B. Richardson. Mesaverde for- 

 mation, near Harper Station, Wyo.; near the 

 Van Dyke coal, Rock Springs, Wyo., collected 

 by F. H. Knowlton and T. W. Stanton, 1896. 



Rhamnus minutus Knowlton, n. sp. 



Plate XVII, figure 2. 



Rhamnus minutus Knowlton [nomen nudum], U. S. Geol. 

 Survey Bull. 696, p. 548, 1919. 



Leaf very small (2 centimeters long, 6 milli- 

 meters wide) but of firm, perhaps coriaceous 

 texture, lanceolate, rather wedge-shaped at 

 the base, and obtusely acuminate at the apex; 

 margin entire but slightly undulate; nervation 

 strong, consisting of a very thick midrib and 

 six pairs of alternate secondaries, which are 

 considerably curved upward and apparently 

 enter the margin; nervilles fairly numerous, 

 unbroken, and approximately at right angles 

 to the secondaries. 



The nearly perfect little leaf figured is the 

 only one observed. It appears to be most 

 closely related to Rhamnus salicifolius Les- 

 quereux and may, indeed, be only a small leaf 

 of that species. The slightly undulate margin 

 and the nervilles at right angles instead of 

 oblique to the secondaries are apparent differ- 

 ences. 



Occurrence: Laramie formation, Erie, Colo. 



Rhamnus marshallensis Knowlton, n. sp. 



Plate XV, figure 3. 



Rhamnus marshallensis Knowlton [nomen nudum], U. S. 

 Geol. Survey Bull. 696, p. 547, 1919. 



Leaf small, linear-lanceolate, rounded and 

 obtuse at the base (apex not seen); margin 

 entire; midrib very strong, straight; second- 



aries numerous, probably about 12 pairs, close, 

 parallel, little curved upward, just reaching 

 the border; nervilles numerous, mainly un- 

 broken, approximately at right angles to the 

 midrib. 



The little leaf figured is all that was ob- 

 served of this form. It was probably about 

 5 centimeters long and is evenly 1 centimeter 

 wide nearly throughout. 



This species appears to be most closely 

 related to Rhamnus salicifolius Lesquereux, 

 from which it differs in its smaller size, rounded 

 instead of wedge-shaped base, and more nu- 

 merous secondaries. 



Occurrence: Laramie formation, wooded 

 bluff south of Marshall, Colo., collected by 

 A. C. Peale, 1908. 



Rhamnus belmontensis Knowlton and Cockerell. 



Rhamnus belmontensis Knowlton and -Cockerell, U. S. 



Geol. Survey Bull. 696, p. 544, 1919. 

 Rhamnus elegans Newberry, New York Lye. Nat. Hist. 



Annals, vol. 9, p. 49, 1868; U. S. Geol. Survey 



Mon. 35, p. 117, pl- 50, fig. 2, 1989. 



This fine species has been well described 

 and figured by Newberry. At the time it was 

 named (1868) it was said to have come from 

 "Miocene sandstone, Belmont, Colo.," a state- 

 ment which reflects the opinion current at the 

 time that all the coal of the West was of 

 Tertiary age. When it was figured in 1898, 

 however, it was said to be from the " Cretaceous 

 (Laramie group), Belmont, Colo.," a state- 

 ment which again reflects the opinion of the 

 time. A question arose as to the exact 

 location of "Belmont, Colo." No town of 

 this name could be located on any available 

 map of the State, and it was suggested by 

 Prof. Junius Henderson, of Boulder, Colo., 

 to whom^,n appeal was made, that it might 

 possibly be a corruption of "Valmont," where 

 the Laramie is present. Quite by accident 

 it was discovered that Belmont was the older 

 name for Marshall, as shown by the following 

 quotation from Hayden's discussion of the 

 region: 46 "In the Boulder Valley the Tertiary 

 coal beds are enormously developed. The Bel- 

 mont or Marshall's coal and iron mines, on 

 South Boulder Creek * * *." This species 

 has not been detected in any of the recent 

 collections from Marshall or elsewhere in the 



«U. S. Geol. and Geog. Survey Terr. Third Ann. Kept, (reprint, 

 1873), p. 129. 



