804 The American Naturalist. [September, 
with three lateral primaries. This is not at all the case. The 
original figure of Dr. Newberry (Illustrations of Cretaceous and 
Tertiary Plants, Pl. xvi.) shows at most only four lobes, and one 
of these is produced by an abnormally strengthened secondary 
arising out of one of the lateral primaries. In Dr. Newberry’s 
description (Later Extinct Floras of North America, Ann. Lyc. 
Nat. Hist., Vol. IX., p. 67) he says: “Leaves . . . three-lobed, 
or sub-five-lobed, . . . two basilar nerves of nearly equal length 
and strength," etc. ; and speaking of the secondaries arising from 
the lateral primaries: * The second or third one on each side is 
often much the strongest of the series, and is then prolonged into 
a small but distinct lateral, triangular, acute lobe, giving the leaf 
a somewhat pentagonal form." He figured only one of the 
leaves in his collection in which, as above stated, this strong 
secondary and supplementary loBe occur only on one side. From 
his description it is inferred that although this sometimes may 
occur on both sides, it is more frequently wanting entirely, and 
the leaves are simply three-lobed. They never have more than 
three primary nerves. 
The large specimen figured by me (Types of the Laramie 
Flora, Pl. xvı.) is of this latter form, and the greater number of 
my specimens, and of all those seen by me (amounting to hun- 
dreds), belong to this class. It is, therefore, safe to say that P. 
nobilis has essentially a palmately three-lobed leaf with two lat- 
eral primaries. 
So much for the general form. Next, with regard to the 
margins and the disposition of the secondaries. It is true that 
in Dr. Newberry’s figure (the specimen I have not seen) the 
secondaries pass directly to the margin, and each one enters ? 
very short, broad, and obtuse tooth, giving the margin an undu- 
late rather than a dentate character. But this undoubtedly varies 
in different specimens, for he describes the secondaries as “ termi- 
nating in the teeth of the margin.” In my specimens there 6 
the greatest diversity in the margins and in the behavior of the 
secondaries on approaching them. In the one figured m p 
“Types,” these do not generally differ from Dr. Newberry $, 
although the secondaries are not all straight or parallel. But I 
