THE FLORA. 



149 



margin from or a little below the middle pro- 

 vided with numerous fine, sharp upward- 

 pointing teeth; midrib strong, straight; second- 

 aries about five pairs, opposite or sometimes 

 alternate, emerging at an angle of about 45°, 

 curving a little upward and joining below the 

 margin, tlience giving rise to a series of loops 

 which appear to have branches entering the 

 teeth; nervilles strong, at right angles to the 

 secondaries, percurrent. 



This species appears to be one of the best- 

 characterized forms belonging to the Laramie. 

 The matrix is a rather coarse sandstone upon 

 which the finer nervation is not well preserved, 

 yet the outline and more characteristic nerva- 

 tion are well shown. It is represented by four 

 specimens, of which the two figured ones are 

 the best. The larger (PI. XXV, fig. 4) is 5.5 

 centimeters long and 4 centimeters broad, and 

 the smaller (PI. XXV, fig. 5) is 6 centimeters 

 long and about 3 centimeters broad. The 

 species is especially characterized by the 

 winged petiole, unecjual base, fine teeth above 

 the middle of the blade, and brachidiodrome 

 nervation. 



In nervation tliis species is very similar to 

 Celastrus cassinefolius Unger,^* but the size 

 and shape are very different. 



Occurrence: Laramie formation. Murphy's 

 coal bank, Ralston County, north of Golden, 

 Colo.; Erie, Colo., collected by N. L. Britton, 

 1885. 



Celastrinites eriensis Enowlton, n. sp. 



Plate XXVI, figure 2. 



Celastrinites eriensis Knowlton [nomen nudum], U. S. 

 Geol. Survey Bull. 696, p. 152, 1919. 



Leaves small, membranaceous, broadly oval, 

 tapering from the broadest point at the middle 

 regularly to an acute apex and to a similar 

 base which extends as a narrow wing to the 

 petiole; margin finely and sharply serrate; 

 nervation consisting of a thin midrib and four 

 or five pairs of camptodrome secondaries; 

 remaining nervation obsolete. 



Tins species is founded on the example 

 figured, which is 3.5 centimeters long and L7 

 centimeters broad, with the petiole about 1 

 centimeter long. The nervation is obscure, 

 about the only thing that can be made out 

 being the midrib and the four or five pairs of 



» Flora tertiaria Helvetiae, vol. 3, p. 67, pi. 121, figs. 25, 26. 



alternate, thin secondaries which emerge at an 

 acute angle and arch just inside the borders. 



This species is found associated witli and 

 may possibly belong to C. alatus, described 

 above. They both have the same serrate 

 margin and winged petiole and approximately 

 the same nervation, but they differ markedly 

 in shape and size, the leaves of C. alatus being 

 several times the size of those of C. eriensis and 

 broadly oblong instead of broadly lanceolate. 



Occurrence: Laramie formation, Erie, Colo., 

 collected by N. L. Britton about 1884. 



Celastrinites cowanensis Knowlton, n. sp. 



Plate XVI, figure 6. 



Celastrinites covmnensis Knowlton [nomeu nudum], U. S. 

 Geol. Survey Bull. 696, p. 152, 1919. 



Leaf apparently of rather thin texture, 

 elliptical, probably about 10 centimeters in 

 length and a little less than 5 centimetere in 

 width; upper portion rather abruptly rounded 

 to a short, obtuse point (basal portion de- 

 stroyed) ; margin strongly toothed, the teeth 

 rather sharp; midrib very slender; secondaries 

 about seven pau's, alternate, thin, at an angle 

 of 30° to 40°, not much curved upward, dis- 

 appearing before they reach the margin; none 

 of the finer nervation preserved. 



Occurrence: Laramie formation, Cowan sta- 

 tion, 10 miles south of Denver, Colo., collected 

 by F. H. Knowlton. 



Family ACEKACEAE. 



Negundo brittoni Knowlton, n. sp. 



Plate XXVI, figures S-10. 



Negundo brittoni Knowlton [nomen nudum], U. S. Geol. 

 Survey Bull. 696, p. 405, 1919. 



Leaves compound, trifoliate; terminal leaflet 

 largest, long-petioled, broadly ovate, rounded 

 at the base, obscurely three-lobed, the lateral 

 lobes 'very short, obtuse, ape.x apparently ob- 

 tusely acuminate; lateral leaflets short-peti- 

 oled, oblong, entire, slightly inequilateral; ter- 

 minal leaflet three-nerved from a point a little 

 above the base, other nerves remote, opposite, 

 effaced at the borders; lateral leaflets with 

 about five pairs of alternate secondaries, which 

 are effaced at their extremities; finer nervation 

 obsolete. 



This well-marked species, which I take 

 pleasure in naming in honor of its collector, 

 Dr, N, L. Britton, of the New York Botanical 



