DESCRIPTIONS OF SPECIES. 65 



entire, sometimes bear a few small teeth. The marginal markings are 

 hardly shown in the largest leaf now figured, and it is represented simply 

 to give the form and dimensions, but in the other figures it will be seen that 

 the variation in the dentation is considerable. 



In form and general aspect the leaf represented in fig. approaches 

 closely to B. grandifolia Ett., as shown by Heer in Fl. Foss. Arct, Vol. II, 

 Abth. II, PI. V, fig. 8, but the marginal dentation is different. The smaller 

 leaves may in a like manner be compared with Heer's figure of B. prisca 

 (Joe. cit, fig. 3), but here again the dentation is unlike that of our specimens. 

 It is, however, possible that further observations will lead to the combina- 

 tion of the two species referred to, B. prisca and B. grandifolia, which are 

 not very unlike with those which occur in such abundance in the locality 

 from which our specimens were derived. The differences, however, are so 

 clearly perceptible that without further information to the contrary the 

 union of these species is not warranted. On PL XLV, fig\ 6, is represented 

 a samara. 



Formation and locality: Tertiary (Miocene). Bridge Creek, Oregon. 



Betula spJ Newb. 



PL LVII, fig. 4. 



Note. — Marked as above on the margin of the plate by Dr. Newberry. 

 Further information lacking, but locality probably Bi'idge Creek, Oregon. — A. H. 



Alnus Alaskana Newb. 



PI. XLVIII, fig. 8. 



Proc. U. S. Nat. Mus., Vol. V (March 21, 1883), p. 509. 



"Leaf large, oblong ovoid, acuminate, rounded, or slightly heart- 

 shaped at base; nervation crowded, sixteen to eighteen branches on each 

 side of the niidrib; margins set with very numerous, small, uniform, acute 

 teeth." 



We have here a strongly marked species of Alnus, apparently distinct 

 from any hitherto described. Its conspicuous characteristics are its very 

 crowded nervation, the broad, oblong ovoid outline, and the minute and 

 regular serration of the margin. In this latter character it resembles A. cel- 

 lulata, living in eastern North America, but differs in the form of the 



MON XXXV 5 



