114 THE LATER EXTINCT FLORAS OF NORTH AMERICA. 



its name lias been given to another larger, broader, obovate leaf found 

 with it, and described by Professor Heer with the name of Phyllites 

 obcordatus. 



The general form of these leaves is not unlike, but the one now 

 under consideration is narrower, slightly unequal at the base, and has a 

 remarkably sparse nervation, as will be seen by referring to the figures. 



Formation and locality: Cretaceous (Dakota group). Blackbird Hill, 

 Nebraska. 



Order ANACARDIACE^ 



Rhus (?) nervosa Newb. 



PI. XXXIII, figs. 5, 6. 



Rhus nervosa Newb. Ann. N. Y. Lye. Nat. Hist., Vol. IX (April, 1868), p. 53; Ills. 

 Cret. and Tert, PI. (1878), PI. XVI, figs. 5, 6. . 



"Leaves pinnate, leaflets oblong or linear in outline, rounded or 

 cordate at the base, pointed above; margins coarsely and acutely sen-ate; 

 nervation pinnate, strong; lateral nerves numerous, leaving the midrib at 

 an acute angle, simple or somewhat branched, parallel, gently arched 

 upward, and terminating in the teeth of the border." 



Collected by Dr. F. V. Hayden. 



The specimens of this plant scarcely afford material for satisfactory 

 classification. They bear a strong resemblance to the pinnate leaflets of 

 some of our shrubby species of Rhus, especially of JR. copallina and 

 JR. typhina. The nervation and marginal serration are essentially the same, 

 and the texture of the leaf would appear to have been similar, but the 

 nerves are stronger and the dentation coarser than in most specimens of 

 these species with which I have compared it. With the trifoliate and 

 oak-leaved species it has little in common, and will not be likelv to be 

 confounded with any of the fossil species which have been described. 



The general form of the leaf is not unlike JR. Meriani Heer (Fl. 

 Tert. Helv., Vol. Ill, PI. CXXVI, figs. 5-11), but the margins of the 

 leaves of that species are not as deeply toothed. 



Formation and locality: Tertiary (Fort Union group). Fort Union, 

 Dakota. 



