40 FOSSIL FLORA OF THP] JOHN DAY BASIN, OREGON. Lmu.i.. 201. 



but into several genera (Quercus, Alnus, Betula, Carpinus, etc.), while 

 Newberr}', judging from what be actually did, would coni])ino them 

 all under his Pojmlus 2>ol yniorphu . I can not l)elieve that they ))elong 

 to Populus. The only living species with which it i,s reasonable to 

 compare them is Populus alha^ which has, it is true, very variable 

 leaves, but they seem of a different type and generically unlike the 

 ones under consideration. I have, therefore, broken up Newl)erry"'s 

 Populus p)olyriiorplia^ placing certain of them under this form. If 

 Newberry's elastic species was maintained it would be polymorphous 

 enough to include them all, but I do not think it will adequately rep- 

 resent the facts to do so. 



In regard to Lesquereux's point of view, it may be said that if 

 extreme examples were selected it might seem logical to call them 

 species, ))ut when the whole are grouped together it is found absolutel}'' 

 impossible to draw any satisfactory line between them. Take, for 

 example, the question of shape. The narrowest possible form may 

 be unlike the broadest form, j^et every step between them can be found. 

 So, also, from the specimens with a wedge-shaped base to those with a 

 a truncate base, and still farther to those with a markedly inivquil- 

 ateral base, there are gradual steps. In the matter of nervation, how- 

 ever, there are onl3"comparativelyslight differences, yet even here the 

 variations are all connected. 



The form most nearly related to this is B. heterodonta Newb., from 

 which it is sometimes almost impossible to separate it. In general, 

 the latter species has much larger leaves, with coarser toothed margins 

 and a more markedly inaequilateral base. Yet these differences come 

 so near l)reaking down that it is sometimes difficult to say where a 

 particular specimen shall go. 



Locality. — Bridge Creek, Oregon. Found a))undantly in all collec- 

 tions (U. S. Nat. Mus., Nos. 8481, 8482). 



Bj:TULA HETERODONTA Ncwb. 



Betula heterodonta Newb., Proc. U. S. Nat. Mus., Vol. V, p. 508, 1883; Later 

 Extinct Floras, p. 64, PI. XLVI, figs. 1-4; PL XLV, figs. 1, 6, 1898. 



As stated under the preceding species, it is almost impossible to dis- 

 tinguish certain of the forms of this species from that. 



Locality. — Bridge Creek, Oregon. Collected by Rev. Thomas Con- 

 don (U. S. Nat. Mus., No. 7071) and" Maj. Charles E. Bendire (U. S. 

 Nat. Mus., No. 8483). 



Betula Bendirei n. sp. 



PI. IV, fig. 2. 



Leaf membranaceous in texture, nearly circular in outline, abruptly 

 I'ounded below to a nearl}' truncate base, rounded similarly above to 



