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pairs of guardian cells, but they are not all in the same horizontal 
plane, one pair, the “subsidiary cells,” of Strasburger being below 
the other. The guardian cells are usually ornamented by silicified 
ridges radiating from the orifice, not a trace of which can be found 
in the fossil under discussion. 
Some of the Bryophytes, notably the liverworts, have stomata 
with more than two guardian cells, but they are loosely cellular 
plants quite unlike this hollow-stemmed plant. 
In the absence of more specific information as to its affinities, 
I have decided to describe this plant under a tentative name, Te 
cognizing the fact that this provisional name may be changed at 
any time provided the fossil can be more definitely placed. I 
had at first given it the name of //i//ia, but as there is a genus of 
this name in Rubiaceae, I have called it Paleohillia, It com- 
memorates the collector and is not intended to imply relationship 
with the Rubiaceous genus. 
Observations upon some Oklahoma Plants. 
By Epcar. W. OLIVE. 
| The botany of Oklahoma is exceedingly interesting, because 
this territory is a borderland region between the Gray's Manual 
and Western Texas Manual regions. Until about five years 48° 
the plants of this district were but little known to botanists, and 
the results of recent collections disclose a flora rich in interesting 
forms. Especially valuable is a “ List of Plants collected by . 
S. Sheldon and M. A. Carleton in the Indian Territory in 1891, 
published as a contribution from the National Herbarium in 189? 
The months of July and August, 1893, were spent in and about 
Payne county, in the very northeast of Oklahoma, about 9° miles 
south of the Kansas line through the Cherokee strip, and about 
150 miles west of Arkansas. This is in lat. 97° W. and is bul? 
few miles south of the parallel bounding on the north Tennessee 
and North Carolina, so that the collections were made just south 
