470 
for showing that these appendages apparently represent former 
basilar lobes of the leaf, which have become detached and gradu- 
ally crowded down the petiole until they finally exist as mere 
stipules at the bases of the petioles or on the branches 
adjacent. The living Platanus occidentalis L. often bears leaves 
on its young shoots which show basilar expansions similar to fos- 
‘sil ancestral forms, and the conspicuous foliaceous stipules at the 
bases of the petioles are familiar objects to us all. It seems rea- 
sonable, therefore, to attribute a similar origin to the conspicuous 
but fugacious stipules on the young saplings and shoots of Lirio- 
dendron Tulipifera, and this view is of course greatly strengthened 
by the discovery of the fossil species now under consideration. — 
It is also of significance to “note that the appendages to the : 
petiole, as represented for the first time in Z. a/atum, made their 
‘appearance in the genus during the Laramie period, a time inter- 
mediate between the era of greatest lobation of the leaves in the 
middle Cretaceous and that of the development of a modern type 
in the Tertiary, in which the former excessive lobation has become , 
greatly modified. This consideration of the subject logically ae 
leads to a discussion of the origin and significance of stipules in : 
general, and raises the question whether they may all have had ay 
similar origin. Such a question can not be decided, or even diss 
cussed at any length, until more data than are now in our posses- : 
sion have been accumulated, and the facts examined from wae 
standpoint here indicated. | 
LIRIOPHYLLUM Lesq. ee 
The genus Liriophyllum was founded by Lesquereux (Hi 
Rept. U. S. Geol. & Geog. Surv. 1876, 482) to include wien 
leaves evidently closely allied to Liriodendron. Under it he su)” 
sequently described three species of leaves and one fruit.* sat 
A comparison of these leaves with the specimen now before 
* L. Beckwithii Lesq. Cret. and Tert. Fl. (1883) 76. p/. 10, / 
L. populoides Lesq, 1. c. 76. pl. r1, f. 1, 2. 
L. obcordatum Lesq. 1. c. 77. og 
Carpites liriophylli ? Lesq. 1. c. 77. pl. 11. fo 5: eer 
_. £. obcordatum was not ea a, i time 3 its original description, be peed 
be found in Lesquereux’ « Posthumous Flora of the Dakota Group fh nert 
_ US.Geol-Suy, (1894) 910. 9428, 67). 
