16 THE LATER EXTINCT FLORAS OF NORTH AMERICA. 



Equisetum sp.? Newb. 

 PI. XXII, figs. 3, 4. 



Fig. 3. "Radicle tubers of Equisetum (not described)." Ills. Cret. and Tert. PI. 



(1878), PI. VII, fig. 4. 

 Fig. 4. "Root of some ligneous plant (not described)." Ills. Cret. and Tert. PI. 



(1878), PI. VII, fig. 3. 



Note. — The only manuscript by Professor Newberry which I have been able to 

 find is a penciled memorandum on the plate referring these to Equisetum, viz : 



Fig. 3. "Tuberous roots of Equisetum sp.?" 



Fig. 4. "Aquatic rootlets of Equisetum sp.?" 



Fig. 3 certainly represents E. globulosum Lesq. , Proc. U. S. Nat. Mus. , Vol, V 

 (September 29, 1882), p. 444, PI. VI, figs. 1, 2; Cret. and Tert, Fl. (1883), p. 222, 

 PI. XLVIII, fig. 3 ; but there is no indication that Dr. Newberry intended so to 

 refer it. — A. H. 



PH^ISTEROG^VIVIT^. 



GYMNOSPERMiE. 



Order CYCADACEiE. 



Nilssonia Gibbsii (Newb.) Hollick. 



PI. XV, figs. 2, 2a. 



Tczniopteris Gibbsii Newb., Boston Journ. Nat. Hist., Vol. VII (1863), p. 512. 

 Nilssonia Johnstrupi Heer, Fl. Foss. Arct., Vol. VI, Abth. II (1882), p. 44, PI. VI, 



figs. 1-6. 



"Frond simple, petiolate, oblong, elliptical in outline, rounded at base 

 and summit; margins entire, midrib strong, straight, smooth; lateral nerves 

 leaving the midrib nearly at a right angle, simple, fine, parallel, numerous." 



The above description was based on a single specimen collected by Mr. 

 George Gibbs from the Cretaceous strata on Orcas Island, Washington, in 

 1858. From the character of the nervation and the entire margins it was 

 supposed to be a fern, but Professor Heer has since obtained a number of 

 specimens of the same plant from the Upper Cretaceous strata of Greenland, 

 which seem to prove that it is the leaf of a cycad. (Fl. Foss. Arct., VI, 

 Abth. II (1882), p. 44, PI. VI, figs. 1-6.) He has named his plant Nilssonia 

 Johnstrupi, but the specific name given by me has priority. 



