158 DESCRIPTION OF SPECIES. 



Populus balsamoid.es? Goepp., var. latifolia. 



Plate XXXI, Fig. 4. 



Goepp., '• Fl. v. Sclioss .," p. 23, pi. xv, figs. 5,6; Heer, " Fl. Tert. Helv.," ii, p. 18, pi. lix; lx, figs 1-3. 



Leaf very large, apparently broader than long, cordate-ovate; borders undulate, 

 crenate ; primary nerves thick; lateral nerves thin, much curved to and aloug the bor- 

 ders; the lower pairs much branched, the other simple. 



This leaf, about 12 centimeters long and 14 broad toward the base, 

 seems to represent a different species from those figured under this name 

 by European authors. It is broader than long, while the leaves of P. 

 balsamoides are, according to Heer, always longer than broad ; it is deeply 

 cordate at base, and the lateral veins, without any basilar veinlets, are com- 

 paratively very thin, much curved and all alike ; the borders are merely 

 crenulate, even obscurely so, while they are more or less deeply serrate in 

 the normal form of P. balsamoides. Fig. 7, pi. lix, of Heer, I. c, represents, 

 however, a leaf with borders obscurely dentate and nearly as large as that 

 of fig 4, cordate at base ; and fig. 1 of pi. lx of Heer shows the lateral nerves 

 of the same character as they are in the American leaf. There is between 

 the fossil leaves a difference as marked as between those of the living 

 Populus balsamifera, Linn., and P. candicans, Ait. This last, though with 

 broader and more or less heart-shaped leaves, is considered a mere local 

 variety of the first. 



#«&.— Florissant. U. S. Geol. Expl. Dr. F. V. Hat/den. 



Populus Zaddachi, Heer. 

 Plate XXXI, Fig. 8 

 " U. S. Geol. Rep.," vii, p. 176, pi. xxii, fig. 13. 



The figured leaf is one of the smallest of this species, and besides 

 differs from the normal form in some points. The secondary nerves 

 descend a little lower; the border teeth, though obtuse and turned upward, 

 have not at the apex the small glands which are generally seen in the 

 small leaves of this species. As these glands may have been destroyed 

 by maceration, as is often the case, and as this species is very common 

 in the North American Tertiary, I consider this leaf as a mere variety. 



Hab.— Florissant. U. S. Geol. Expl. Dr. F. V. Hayden. 



