with Descriptions of New Species of Fossil Plants. 



dentation is also generally more acute in the leaves of the mul- 

 berry, and the leaves more pointed. The nervation of these 

 fossil leaves is almost precisely that of our common species of 

 Tilia, but in that the marginal dentation is much sharper. In a 

 Southern species, however, T. heterophyUa, I have found leaves 

 which seem to be the exact counterpart of these ; leaves with a 

 roughish surface, strong and regular nervation, just after this 

 pattern, and with a coarse, obtuse, and regular dentation. 1 

 am therefore inclined to refer these fossils td Tilia, and to re- 

 gard them as the relics of a species closely allied to, if not 

 identical with, T. heterophylla. 



Formation and Locality. Miocene strata, near Fort Clarke. 

 (Dr. Ilayden.) 



Rhus nervosa (n. sp.) 



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

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

 serrate; nervation pinnate, strong; lateral nerves numerous, leav- 

 ing the midrib at an acute angle, simple or somewhat branched, 

 parallel, gently arched upward, and terminating in the teeth of the 

 border. 



The specimens of this species scarcely afford material for sat- 

 isfactory classification. They hear a strong resemblance to the 

 pinnate leaflets of some of our shrubby species of Rh us, speci- 

 ally of R. copaUina and R. typhhui. The nervation and margi- 

 nal 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 spe- 

 cies with which I have compared it. With the trifoliate and 

 oak-leaved species it has little in common, ami will nor 1»<> 

 likely to be confounded with any of the fossil species which 

 have been descrihed. 



The general form of the leaf is not unlike /.'. Meriani, Beer 

 (Op. cit. Taf. exxvi. figs. 5-11), hut tin- margins of the leaves 

 of that species are not as deeply toothed. 



Formation and Locality. Miocene strata. Fori Union, 

 Dacotah. (Dr. Ilayden.) 



