Know._ton: Fossir Plants From Porcupine Burre 709 
living species is usually more unequal-sided at base than the fossil, 
but there is variation in this respect, certain of the leaves being 
almost regular below. In the fossil leaf the midrib is propor- 
tionally thicker, more zigzag and the first pair of lateral ribs more 
curved upward. The nervilles and finer nervation are practically 
the same. 
I have named this species in honor of the collector. 
AGE OF THE BEDs AS INDICATED BY THE PLANTS 
The number of species, although small, is sufficient to give a 
pretty clear idea of the age. Four species have been enumerated, 
three of which were previously known. Of these Onoclea sensibilis 
Sossilis has only been found in the Fort Union beds, at the mouth 
of the Yellowstone and in the Canadian Upper Laramie. Aralia 
notata was described originally from the Fort Union and has only 
been found in beds of similar.age in the Yellowstone National Park. 
Glyptostrobus Ungeri, if this be the proper name by. which to call 
it, is abundant in the Fort Union beds, and has also been found 
elsewhere. The new species (Zi/ia Weedit) is of uncertain affinity 
_and is therefore of little value in this instance. The things it most 
resembles belong to the Fort Union. 
Taking into account the locality whence these plants came the 
character of the material and the species as above enumerated, I do 
‘not hesitate to say that the beds in which they occur should be 
referred to the Fort Union. 
Explanation of Plate 26 
Fic. 1, Fruiting frond of Onoclea sensibilis fossilis Newb. 
Fics. 2-4. Sterile fronds of same. 
