CRETACEOUS FLORA. 1] 
Populites.] 
long petiole; borders entire, undulate; nervation obscurely tripalmate; and craspedodrome 
primary lateral nerves emerging at a distance above the basal borders, 
[have figured two fragments of this species, in order to show the real form of 
the leaves. In comparing the two figures it will be seen that in Pl. A, fig. 2, the 
primary lateral nerves are at a slightly greater distance above the basal border than 
in Pl. B, fig. 1, a fragment which has exactly the same characters as in the leaf in 
Cret. Fl. loc. cit. The leaves are generally large, about 9 cm. long and nearly as broad. 
The lateral nerves about parallel, at an angle of divergence of 40°, branch under- 
neath, or sometimes dichotomously, the ultimate division becoming very thin, but 
running into the border as sub-craspedodrome, a character rarely remarked in 
the living species of Populus. It is for this reason that I have preserved for the 
leaves having this peculiar character the name of Populites. 
The genus Populus was abundantly represented in the Cretaceous of North 
America. In his Phyllites de Nebraska, Heer has described one species. Prof. 
Newberry has three, also from Nebraska, in his Notes on the Extinct Floras. I 
have added to the number three in the Cret. Fl. from Kansas and Nebraska, and one 
described here below, or already 8 species. And still Heer has found four species in 
the specimens from the Cretaceous of Atane, Greenland, a formation which, by the 
number of its species identical with those of the Dakota group, is evidently of the 
same age. Even the first and only leaf of a dicotyledon found at Korne, a stage 
of the Cretaceous of Greenland lower than Atane, is that of a Populus. It is 
remarkable that all the species of Greenland have a camptodrome nervation. 
Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. 
Mus. Reg. Nos. 5155 Cc, 5377. 
PopuLITES cycLopHYLLUS? Fleer. 
Proceed. of the Acad. of Nat. Sci. of Philadelphia, 1858, p. 266. Lesqz., Cret. Fl. p.59, Pl. IV, f. 5; Pl. 
XXIV, f. 4. 
Leaves round, entire, slightly undulate rounded or truncate to the petiole, texture 
rather thin; nervation pinnate; lower lateral nerves, emerging at the base of the leaves all 
craspedodrome, straight, simple, except the lowest pair branching underneath. 
The species is still uncertain, as I remarked in the first description /.c, I have 
referred to it leaves answering to the description of Heer, but the author does not 
consider my reference as right. I have not seen any original specimen nor any 
ftgure of it. The specimens from Minnesota are mere fragments, not sufficient for a 
positive determination. 
Hab. North side of the Big Cottonwood river, near New Ulm. 
Mus. Reg. No. 5155. 
