8 THE LATER EXTINCT FLORAS OF NORTH AMERICA. 



16 to 20 centimeters; width, 10 millimeters; margins undulate below, irregu- 

 larly and coarsely toothed above ; nervation fine, but distinct ; branches all 

 forked, leaving midrib at an angle of about 45 degrees, all twice or three 

 times forked." 



Only the upper part of the frond of this fern appears on the specimens 

 examined, but these show a species apparently distinct from any hitherto 

 described. In general form the pinnae resemble those of Pteris penncs- 

 formis Heer (Fl. Tert. Helv., Vol. I, p. 38, PL XII, figs. 1-ld), and P. pseu- 

 dopennceformis Lesq. (Tert. FL, p. 52, PL IV., figs. 3, 4), but it differs from 

 the first by being a stroug-er plant, with wider and more coarsely toothed 

 pinnae, and less simple nervation; from the second, by the same characters 

 and in having the nervation less crowded, the nerve branches issuing at a 

 greater angle, and oftener forked. 



Pteris erosa Lesq. (Tert. FL, p. 53, PL IV, fig. 8) has broader pinnae, 

 of which the margins are set with finer and more numerous teeth. 



The species is dedicated to Mr. I. C. Russell, who first collected it, in 

 Vermejo Canyon, New Mexico. It has also been collected at Walsenburg, 

 Florence, and Grolden, Colorado. 



Formation and locality: Cretaceous (Laramie group). Vermejo Canyon, 

 New Mexico. 



Onoclea sensibilis fossilis Newb. 



PI. XXIII, fig. 3; XXIV, figs. 1-5. 



Onoclea sensibilis, L., Newberry in Ann. N. Y. Lye. Nat. Hist., Vol. IX (April, 1868), 

 p. 39; Ills. Cret. and Tert. PI. (1878), PI. VIII, fig. 1; IX, figs. 1-3. 



"Frond pinnate, large; pinnae, lanceolate in outline, with waved mar- 

 gins, more or less deeply lobed or pinnatifid, connate at their bases, form- 

 ing- a broad wing on the rachis of the frond; nervation strongly marked, 

 more or less reticulated, the nerve of each lobe or pinnule springing from a 

 common trunk, having a dendroid form, with waving branches, which often 

 unite to form elongated lacunae, of which the largest border the rachis of 

 the pinnae on either side, and are formed by the nerve branches of each 

 lobe reaching over and touching, or closely approaching, the base of the 

 nervation of the next superior lobe or pinnule." 



The collection of fossil plants made at Fort Union by Dr Hayden 

 contains a great number of examples of this beautiful fern, showing the 



