THE CRETACEOUS RIM OF THE BLACK HILLS. 259 



I ; i. e., No. 12 of section I corresponds to the upper 30 feet of 

 No. 4, section II. 



At Minnekahta Station, in an ornamental heap of various min- 

 erals and rocks from the Black Hills, there were a number of 

 fragments of cycads and fossil wood. We were told that these 

 came from a ridge two miles to the southeast of the station that 

 rises above the Red Beds and shows at its base low buttes and a 

 considerable thickness of Jurassic. This was not visited, but it 

 was evident that the summit of this ridge was formed by the hard 

 sandstone No. i of section I (No. 5 of section II), which is con- 

 tinuous to Evans Quarry. The position of the cycad and fossil 

 forest bed here is doubtless the same as on the opposite side of 

 the valley where it was studied. 



The occurrence of two other specimens of cycadean trunks, 

 though apparently belonging to a different species, in the same 

 general horizon on the east side of the Black Hills, and of silici- 

 fied wood in the northern districts, seems to indicate that the 

 same relations obtain on all sides, and this will probably be found 

 to be the case. 



The fossil plants of the lower horizon were sent to Professor 

 Fontaine for determination, and the following extracts from his 

 report upon them will show that my interpretation of their sig- 

 nificance at the time of their discovery was for all practical pur- 

 poses correct. 



"The best preserved fragments are scattered leaflets, and the 

 summits of the ultimate pinnae of ferns, which are the parts of 

 those plants which have great value in fixing species. The fol- 

 lowing are the plants : 



" I. The summits of ultimate pinnae of a fern, which is decid- 

 edly like Asplenium Dickso?iianum Heer, from the Kome beds of 

 Greenland. It has also something of the character of the widely 

 diffused Potomac plant, Thyrsopteris rarinervis, but is, I think, 

 nearer Heer's plant. 



"2. Some ends of the ultimate pinnae of a small fern with the 

 facies of a Gleichenia. This is nearest to Heer's Gleichenia Zippei, 

 from the same Kome beds, but the pinnules are rather more acute 



