wAitn.) 



LIST OF SrEClES ILLUSTKATEU. 549 



northern drift was observed, loriiiiug a layer about two feet thick, close 

 down to the water's edge. One hundred miles below Fort Buford a tine 

 deposit of typical Fort Union plants was found, the light slate-colored 

 marl containing them being, however, quite soft. At Little Kuife Creek 

 another bed was examined. The Fort Union groui) is the only deposit 

 in view throughout all this region. I'lants were seen at nearly all points 

 that were examined, and at Fort Stevenson I visited a range of low red 

 buttes three miles east of the fort, where I collected a number of good 

 specimens. They closely resembled the forms of the Lower Yellowstone 

 and those previously described from various points within the Fort 

 Union group. 



Below this poiut the country is more flat, the hills are lower and 

 more distant from the river, and there is evidence that the Laramie de- 

 posits are passing below the surface. Square Butte, eight or nine 

 miles above Bismarck, is capped by strata that appear to occupy the 

 summit of the formation. 



LIST OF SPECIES ILLUSTRATED. 



The proportions which this paper has assumed preclude any explana- 

 tory remarks upon the figures which I have selected to illustrate the 

 recent collections above described from the Laramie group, and all that 

 can be added in explanation of them is a simple list of the names of the 

 species as they have been decided upon up to this time, leaving more 

 ample discussion of the nice points involved, and the statement of the 

 evidence for or against these determinations, for a subsequent publica- 

 tion. This effort must be regarded as tentative, and subject to much 

 alteration as more thorough study of all the material in hand shall 

 throw additional light upon the many knotty problems involved. 



CRYPTOGAMS. 



Fucus lignitum, Lx. Phite XXXI, Figs. 1, 2. 



PointotKucks, W,^ omiug ; white saudstoiie Ijed east of station (Fig. 1). Burus's 

 Rancb, Moutana (Fig. U). 



Spiraxis bivalvis, u. sp. Plate XXXI, Fig. 3. 

 Head of Clear Creek, Montana. 



CONIFERS. 



Ginkgo Lar(imieiisis,Wan\, Science, Vol. \', June 19, 1SS5, p. 49(5, tig. 7. 

 Plate XXXI, Fig. 4. 



Point of Rocks, Wyoming; gray sandstone bed uortli of station. 



Giidgo (idiantoides, Ung. Plate XXXI, Figs. 5, C. 

 Seven Mile Creek, Montana; SparganlMni l)ed. 



bW 



