knowlton.] DESCRIPTION OF SPECIES. 63 
where it is preserved, not even to its base, being eighteen millimeters long and the 
petiole nine millimeters. The areolation is clearly defined in very small square or 
polygonal meshes, formed by close, thick nervilles anastomosing with veinleta 
parallel to the nerves and their divisions, the parietes being as thick as the veins. 
The same kind of nervation is observable upon the lower surface of the leaves of 
the living Trapa natans L., which, though comparable to these fossil ones, have the 
borders deeply toothed and are of much thicker texture. In this species the leaves 
appear as membranaceous and pellucid, for the nervation and areolation seem drawn 
in black on the yellowish substratum of the laminae. 
On comparing the fossil leaves with the living T. natans many points 
of resemblance are found. They have apparently the same habit, and, 
with certain limitations, the nervation is quite similar. Strong confirm- 
atory evidence is supplied by the fact that this plant is always associated 
with undoubted aquatic plants, such as Lemna, Pistia, Equisetum, 
etc., and in Canada Sir William Dawson has found the leaves associated 
in the same beds with fruits of Trapa. He speaks of them as follows: 1 
These fruits and leaves are all from the Lower Laramie, with the exception of 
one doubtful example from the Upper Laramie of Great Valley. The localities are 
Bad Lands, Red Deer and Rosebud rivers, and Pincher Creek. In some of these local- 
ities they are associated with Lemna scutata and Phraginites. 
The leaves seem to be very variable in form and dimensions, and in Mr. Tyrrell's 
collection there are fragments of much larger leaves than any figured by Lesquereux. 
In another place he says: 
In Mr. Tyrrell's collections from Red Deer and Rosebud rivers there are fruits 
similar to Heer's species {Trapa borealis) and leaves not distinguishable from those 
described and figured by Lesquereux. We have thus a probability that the fruits 
and leaves belong to the same species* 
From the above statement it appears that this species has been found 
in Wyoming and in various Canadian localities under practically similar 
conditions — that is, associated with aquatic plants and, in one, with 
fruits of Trapa. The presumption of their identity is thus strength- 
ened, and also their reference to the genus Trapa. 
During the season of 1896 large numbers of leaves in a very perfect 
state of preservation were found by Mr. T. W. Stanton and myself in 
Converse County, Wyoming, in clay beds in the lower portions of the 
true Laramie. 
In 1883 Professor Ward obtained at Burns's ranch, on the Lower 
Yellowstone Kiver, Montana, a large number of finely preserved leaves 
which he referred to Lesquereux's Trapa f microphylla. 2 In describing 
them he said: 
The size, shape, and nervation of these leaves are substantially identical with 
those of Point of Rocks, and until fruit is found for both it will be necessary to 
regard them as the same species. 
1 have examined all of Professor Ward's material and have reached 
results somewhat opposed to this determination. The size and shape 
'Foss. Fl. of Lar. Form, of Canada, Trans. Roy. Soc. Canada, Vol, IV, p. 31. (1886). 
2 Types Lar. FL, p. 64, PI. XXVIII, figs. 2-5 (1887). 
