544 FLORA OF THE LAKAMIE GROUP. 



creased by saturation, which was well shown in those fragments that 

 were taken from below the surface of the water in the river. The sur- 

 faces of the leaves often form planes of cleavage, and thus many beau- 

 tiful specimens were obtained, but the tendency to forsake these i)lanes 

 and break out at other places rendered many of the specimens frag- 

 mentary. Some very perfect specimens of Trapa were obtained. This 

 plant, as is well known, grows in deep water, from a long submerged 

 stem, which reaches the surface and bears at its summit a cluster of 

 small roundish leaves on petioles of ditferent lengths, which are so ar- 

 ranged upon the stem that all the leaves can lie upon the surtace of 

 still water. The longest petioles bear the outer circle of leaves and 

 successively shorter ones those of circles nearer and nearer the cen- 

 ter, where the leaves are small and sessile. Several of my specimens 

 as well as some of those collected the year previous by Dr. White 

 show these concentric rosettes of leaves in an interesting way. 



The Cocculus leaves are rare in these beds, but several of the best 

 specimens were nevertheless found here. Numerous fine specimeus of 

 Populus were obtained, only a few of which are figured for this paper. 

 The sharply serrate, more or less elongated, leaves that seem to belong 

 to the order Celastrinete were among the most numerous and are nearly 

 or quite all new to science. A few very fine specimens of the remarka- 

 ble tapeworm-like Cryptogam mentioned above were found here, but this 

 form is not yet figured. The bulbous tufted base is much smaller than 

 in the Iron Elulf specimeus, but the remarkable serpent like rays, with 

 inflated transversely-ribbed heads and finely-toothed middle portion, 

 are shown with great clearness. 



These two beds (Iron Blufi'aud Burus's Kauch) appear to me to form 

 the base of the Fort Union deposit, and present a flora entirely difl'erent 

 from that of any other yet discovered. It is remarkable that the Trapa 

 found in both of them appears to be the same species as that found so 

 sparingly in the fine white sandstone layer at Point of Eocks, and what 

 is still more remarkable, I also found at Burns's Eauch a few specimens 

 of the characteristic Point of Eocks plant Pistia corrugata. I am in- 

 clined to regard these two beds as synchronous, and the differences in 

 the rest of their floras may be accounted for by differences of latitude 

 and the other conditions previously jwinted out. Both seem to occupy 

 the base of the Laramie and to overlie the same marine Cretaceous de- 

 l)osit. 



In ascending the Yellowstone the next locality is that known as 

 Seven Mile Creek, or Gleason's Eanch. The little stream called Seven 

 Mile Creek, five or six miles above the mouth of which the ranch is 

 located, is situated about seven miles below old Fort Glendive, making 

 it about ten miles below the village of Glendive. Its lower valley is 

 open and shows no exposures, but at Gleason's Eauch it has narrowed, 

 and is bounded by hills that rise on the left bank, by a series of terraces, 



