242 DESCRIPTION OF SPECIES. 



BETULACE^E. 



BETULA, Linn. 



Betula parce-dcntata, sp. nov. 



Plate L, Fig. 12. 



Leaf ovate, rounded in narrowing to the base, tapering up to a short acumen, 

 dentate; secondary nerves craspedodronie ; nervilles simple, at right angles to the 

 nerves. 



A comparatively small leaf, 5 centimeters long, 3 broad in the middle, 

 the broadest part simply dentate; lower teeth turned outside, the upper 

 curved upward ; the lower basilar secondary nerves are at a slightly 

 more acute angle of divergence, branching outside. 



Among the fossil plants the affinity of this leaf is with Betula prisca, 

 a very variable and common species of the Miocene. It is especially com- 

 parable to the figures given of that species by Heer in the "Flora of Sacha- 

 lin," "Fl. Arct.," vol. v, pi. vii, figs. 3,4, and pi. ii, fig. 8, of the supplement 

 to the same Flora. Its analogy is also marked with the leaves I have 

 described as Betula cequalis, Lesqx., " Mem. of the Museum Comp. Zool. 

 Harvard," p. 3, pi. 1, figs. 2, 3, 4. It differs from both by the shorter 

 more broadly ovate form and the basilar nerves, which are at a more 

 acute angle of divergence. From the last species it is also distinct by the 

 branching of the lower lateral nerves, which are simple and less curved 

 in B. cequalis. 



Hah. — John Day Valley, Oregon. 



Betula elliptica, Sap. 



Plate LI, Fig. 6. 

 Sap., "fit.," iii, 1, p. 59, pi. v, figs. 3, 4. 



Leaves long-petioled, elliptical, equally narrowed from the middle downward to 

 the petiole and upward to an acumen, doubly dentate; secondary nerves subopposite, 

 oblique, branching toward the apex. 



The leaf is somewhat larger than the one described by Saporta. As 

 it agrees in all its characters, it cannot be separated from the mere differ- 

 ence in size. It is 8J centimeters long, nearly 4 broad, and the petiole 2 

 centimeters. The lateral nerves, seven pairs, with a thin basilar marginal 

 vein, diverge at an angle of 30°. 



Hah. — John Day Valley, Oregon. 



