68 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA, 



figs. 5, 6), which bears much smaller, more regular tubercles, nearly exactly 

 oval. In both these species, the articulations are inflated ; in ours, they are 

 strangled, as seen in the figures. 



Habitat. — Barrell's Springs {Dr. F. V. Hayden), Carbon Station, Wyom- 

 ing. The specimens of this locality are too fragmentary for positively 

 demonstrating specific identity. 



Equisetum Isevigatum, Lesqz. 

 Plate VI, Figs. 6, 7. 



EquisetumT Iwvigatum, Lesqx., Aunnal Report, 1873, p. 395. 



Stem or rhizoma thick, distantly and obscurely articulated. Irregularly wrinkled in the length ; 

 articulations marked by round scars, distant from each other. 



The only specimens obtained of this species are figured here. Tliey 

 seem to represent remains of a large species of Equisetum by the indistinct 

 articulations and the scars perceivable around them. The large specimen 

 (fig. 7) is only part of a stem or rhizoma divided in its length ; the articula- 

 tion is marked merely by two scars, round in the center, with a row of oval 

 impressions placed starlike around it, as it is sometimes the case in large fossil 

 species of Equisetum. It is narrowed above the articulations, and ajjpears 

 enlarged at the nodi, but probably by a compression of the stem, more 

 marked there than it is above ; the surface of the specimen is smooth, merely 

 impressed by irregular wrinkles, not true equal stride. The other smaller 

 specimen (fig. 6) has its articulation marked on one side by a round scar, and 

 on the other by the outside of a scar of the same form, to which is attached 

 an articulated branch, flattened in the middle, then divided in two at its end, 

 either by normal separation or by splitting from mechanical compression. 

 This part resembles somewhat fig. 2 of the same plate, for the branch repre- 

 sents apparently less inflated tubercles, or the division of a rhizoma slightly 

 strangled at the articulations and disfigured by compression. I therefore 

 consider these fragments as representing a species or perhaps two different 

 species of Equinetum, the one with a much larger stem and the scars marked 

 by an outside row of oval impressions ; the other smaller, diflfering from 

 Equtsetum Haydenii, especially by its smooth surface, the less distinct articu- 

 lation.s, with more distant round scars, and the irregular form of the tubercles. 

 Characters of this kind, and too indefinite, cannot be considered as speci^fic, 

 perhaps. They are to be carefully considered, however, as the specimens 

 belong to a stage of the Tertiary different from those of the former species. 



Habitat. — The large specimen (fig. 7) is from Sand Creek, Colorado, 

 eight feet above coal ( W. H. Holmes); the small one from Golden {A. Lakes) 



