66 THE LATER EXTINCT FLORAS OF NORTH AMERICA. 



leaf and in the greater number of lateral nerve brandies. From A serrata, 

 figured, on PL XXXIII of this monograph, it is at once distinguished by 

 the very much finer marginal dentation, as well as by the greater number 

 of nerve branches. The remarkably fine denticulation of the margin is a 

 character which distinguishes it from A. Kieffersteinii and A. nostratum the 

 species most commonly preserved, in the Tertiary rocks. 



Formation and locality: Tertiary (Miocene). Kootznahoo Archipelago, 

 latitude 57° 35', longitude 134° 19', Alaska. Collected by United States 

 steamer Saginaw, Februarv 18, 1869. 



Alnus serrata Newb. 



PI. XXXIII, fig. 11. 



Ami. N. Y. Lye. Nat. Hist., Vol. IX (April, 1868), p. 55; Ills. Cret. and Tert. PI. 

 (1878), PI. XVI, fig. 11. 



"Leaves oval or elliptical, slightly cordate at the base, rounded or sub- 

 acute at summit; margins serrate throughout, serrations fine, sharp, and 

 appressed below, coarse and double above; nervation pinnate, strongly 

 marked ; basilar pair of lateral nerves short and simple, upper ones branched 

 near the extremities." 



Collected by Dr. F. V. Hayden. 



These leaves have nearly the form of Alnus Kieffersteinii Ung. (Chlor. 

 Prot, p. 115, PI. XXXIII, figs. 1-4), and a nervation similar in kind, but 

 more crowded. The marginal serration is also coarser. 



Formation and locality Tertiary (Eocene !). Banks of Yellowstone 

 River, Montana. 



Alnus serrulata fossilis Newb. n. sp. 



PL XLVI, fig. 6. 



Among the leaves from Bridge Creek occurs one very beautifully 

 preserved, which is represented in fig. 6, PI. XLVI. It will be seen at a 

 glance that it closely resembles the leaves of A. serrulata, and I have been 

 unable to find any characters upon which to base a distinction. More 

 material will of course be needed before the fact may be considered estab- 

 lished that our most common alder was growing in the Tertiary. There 

 would be nothing surprising, however, in such a discovery; indeed, it was 



