67G GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



The two stems sliowu in the upper part of fig. 6 show a distinct hne 

 of tubercles a1x)ut tlie sHylit constriction. Tliey probably represent the 

 lower portions of the stems. 



Habitat: Yancey Fossil Forest, beds near the uprig-ht stumps (fig-. 

 6); collected by F. TT. Knowlton, August 28, 1888. End of Specimen 

 Ridge, opposite Junction Ijutte, near large upright stumps; collected by 

 Lester F. Ward and E. C Alderson, August 25, 1887. Yellowstone River, 

 one-half mile below Elk Creek, at base of bluft'; collected by F. H. 

 Knowlton, August 27, 1888. Cliff west of Fossil Forest Ridge; collected 

 by Ward and Knowlton, August 15, 1887, 



Equisetum deciduum n. sp. 



PI. LXXXL tig. •">. 



Stems large, many-ribbed, articulate, sheathed; sheaths short, without 



teeth. 



This form is represented by several specimens, all very fragmentary 

 and obscure. It has the stem 15 mm. in diameter, and the sheath 14 

 mm. in length. The diaphragm is clearly shown in 2 specimens, and 

 appears to have been thick. The sheath is close and without teeth, 

 which probably inidcates relationship of this species with living species, 

 such as E. hiemale, E. rohustmi, etc., having deciduous teeth. 



Habitat: Yellowstone River, one-half mile below the mouth of Elk 

 Creek, base of bluff (fig. 5); collected by F. H. Knowlton, August 27, 

 1888. Fossil Forest Ridge, bed No. 6, "Platanus bed;" collected by 

 Ward and Knowlton, August 19, 1887. 



CONIFERS. 



PiNUS GRACILISTROBUS n sp. 



PL LXXX, fig. 12. 



Cone lanceolate, about 12 nnn. in diameter and about 45 mm. long 

 (neither base nor apex preserved); scales in 7 or 8 rows, regularly 

 rhomboidal in shape, about 6 nnn. in transverse and about 5 nnn. in vertical 

 dimension; scales umbonate, with usually 3 slight projections on the 



lower angle. 



The specimen figured is the only one found of this species. At first 



