L52 Sensitive Fern 
Newberry * is said to differ from it only in possessing a more 
robust habit. Specimens of the fossil fern are said to practically 
duplicate both the mature sterile and fertile leaves of our fern, 
and the transitional leaves as well. According to Dr. Knowlton, 
the fossil fern has been found only in the Fort Union Beds at 
the mouth of the Yellowstone, and in the Canadian Upper 
Laramie. 
*O. sensibilis fossilis Newberry, Ann. N. Y. Lyc. Nat. His. 9 : 39. 1898. See 
Lesquereaux, Ill. Cret. and Tert. Plants, PJ. VIII., Figs. 1-0, Figs. 1-5. 1878. New- 
berry, Later Extinct Floras, 8: Pl. XXIII., Fig. 3; Pl. XXIV., Figs. 1-5. 1898. Knowl- 
ton, Bull. Lon. Bot. Club. 705-706, Pl. XXVI., Figs. 1-4. 1903. 
