DESCRIPTIONS OF SPECIES. 15 



approaches more nearly to the larger forms of the Mesozoic rocks. It 

 may be compared with E. robustum Newb., this volume, page 15, PI. XVI, 

 figs. 1, 2, but the stem is broader, the flutings double the number, and the 

 teeth much shorter and blunter than in that species. E. procerum Heer 

 (Fl. Tert. Helv. Vol. Ill, p. 158, PI. CXLVI, fig. 1), from Locle, Switzer- 

 land, is larger, but differs widely from it by its coarser fluting, long - and 

 furrowed teeth. 



Formation and locality: Tertiary (Miocene!). Currant Creek, Oregon. 



Equisetum robustum Newb. 

 PI. XVI, figs. 1, 2. 

 Boston Journ. Nat. Hist., Vol. VII (1863), p. 513. 



"Stem robust, 8 lines wide, with about 24 strongly marked furrows; 

 sheaths long; teeth long-pointed, acute, as many as the furrows; internodes 

 a little longer than the diameter of the stem." 



There is no living species of Equisetum which attains the size of the 

 fossil before us, though it does not rival in this respect those found m the 

 older Mesozoic rocks. Between the living and older extinct species it 

 seems to form a connecting link, a stepping-stone by which the Calamites 

 of the coal period and the gigantic Equiseta of the Trias have come down 

 to the humble dimensions of their present representatives. 



There is no described Tertiary species with which it will be likely 

 to be confounded. E. procerum Heer (Fl. Tert, Helv. Vol. Ill, p. 158, PI. 

 CXLVI, fig. 1), is even larger, but will at once be distinguished from it by 

 its smoother stem and far more numerous and less acute teeth. 



Formation and locality: Cretaceous (Puget Sound group). Belling- 

 ham Bay, Washington. 



Equisetum Wyomingense Lesq. 



PI. LXV, fig. S. 



Hayden's Ann. Rept., 1873 [1874], p. 109; Tert. Fl. (1878), p. 69, PI. VI, figs. 8-11. 



Formation and locality: Tertiary (Green River group). Green River, 

 Wyoming. 



Note. — So identified by Dr. Newberry, as indicated by memorandum on plate 

 and label on specimen, but further information lacking. — A. Ii. 



