698 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



Salix elongata ? 0. Web. 

 Salix elongata O. Web. Lesquereux: Tert, PL, p. 169, PL NXII, figs. 6, 7. 



A single quite well preserved specimen that seems to belong to this 

 species. The nervation, however, is not well preserved, but as nearly as 

 can be made out it may be referred to this form. 



Habitat: Fossil Forest, lower stratum, No. 1221 of Hague's Yellow- 

 stone National Park collection; collected by Arnold Hague, September 

 24, 1884. 



BETULACEJE. 



Betula iddingsi n. sp. 

 PI. LXXXYI, figs. 4, 5. 



Leaves membranaceous, ovate, slightly unequal-sided, rather abruptly 

 rounded to the base, more prolonged above; margin regularly toothed from 

 near the base, teeth slightly unequal, a little hooked; nervation pinnate 

 and craspedodrome ; midrib well marked, straight; secondaries about 10 

 pairs, mainly alternate, occasionally opposite, arising at an angle of about 

 45°, straight or nearly so, terminating in the larger teeth, often with forks 

 near the margin, all of which enter the other teeth; uervilles obscure, but 

 apparently percurrent and at right angles to the secondaries; finer nerva- 

 tion not preserved. 



This species is represented by 3 very perfect leaves, all of which are 

 preserved on the same piece of matrix The most perfect one figured is 

 8 cm. in length and 4.5 cm. wide, while the other is about 8 cm. long and 

 less than 4 cm. wide. The petiole belonging to this specimen is 7 mm. 

 in length-. 



This species somewhat resembles a number of described forms, as, for 

 example, Betula stevensoni Lx., 1 from Carbon, Wyoming, from which it differs 

 somewhat in shape, number of pairs of secondaries, and in the more regularly 

 serrate margin. Betula elliptka Sap., as identified by Lesquereux 2 from 

 John Day Valley, Oregon, is perhaps closer, yet this differs in having only 

 6 or 7 pairs of secondaries and also in the teeth. Betula parce-dentata 

 Lx., from the same locality, has the same kind of teeth, but differs in size. 



'Tert. PI., p. 139, PI. XVIII, figs. 1-5. 

 2 Cret. and Tert. PI., p. 212, PI. LI, tig. 6. 



