THE LATER EXTINCT ELORAS OF NORTH AMERICA. 



By John Strong Newberry. 



DESCRIPTIONS OF SPECIES. 



OEYPTOGAMIA. 



PTERIDOPHYTA. 



Order FILICINiE. 



Lygodium Katjlfussi Heer. 



PL LXII, figs. 1-4. 



Fl. Skopau; Beitr. naher Kent. Sachs. -Thuring. Braunkohl, Vol. XVIII (1861), 



p. 409, PI. VIII, fig. 21; IX, fig. 1. 

 Lygodium neivropteroides Lesq. Hayden's Ann. Rept. 1870 [1872], p. 384; Tert. Fl. 



(187S), p. 61, PL V, fig. 4-7; VI, fig. 1. 



Dr. C. A. "White has collected from the Green River shales a splendid 

 series of the fronds of a Lygodium which is apparently identical with that 

 described by Lescraereux under the above name. These illustrate the 

 growth of the plant far better than those he figures, and some of the more 

 interesting and instructive ones are therefore now figured. Coming all from 

 the same locality, indeed thickly impacted together and having the same 

 nervation, they unquestionably represent a single species, and yet it will be 

 seen that if diversity of form were accepted as affording specific distinctions 

 half a dozen species might be made from them; hence we are taught by 

 them that the fossil species of Lygodium already described are based on 

 too insufficient material, and should have comparatively little weight until 

 confirmed by further evidence. The number of figures now given, how- 

 ever, enable us to define this species in such a way that it is not liable to be 

 mistaken. 



As these fronds occur in the rock, the margins seem to be undulated 

 and the lobes considerably curved and twisted. How much of this is due 

 mon xxxv 1 i 



