4 
like the living species that it is impossible to distinguish theni, 
and they should probably be united with it. We here have a 
striking illustration of the wide distribution of a species which 
has retained its characters both of fruit and leaf quite unchanged 
through long migrations and an enormous lapse of time. 
In Europe the Tulip-tree, like many of its American asso- 
ciates, seems to have been destroyed by the cold of the Ice 
Period, the Mediterranean cutting off its retreat, but in America 
it migrated southward over the southern extension of the conti- 
nent and returned northward again with the amelioration of the 
climate. 
Of the species of Lériodendron found in the Dakota group of 
Kansas, the leaves of one (Z. Primevum, Newb., Later Extinct 
Flora of North America, p. 12), are much like those of the living 
species, but are considerably smaller. Another species (/. 
Meekii, Heer), has small fiddle shaped leaves (Plate LXI., fig. 
3-4). Prof. Heer considers this identical with L. primevum, but 
the form is quite different and no connecting links have been 
found. From the Amboy clays we have obtained one leaf 
which apparently represents ZL. Meekii; it is typically fiddle- 
shaped, though larger then the Dakota leaves. 
Prof. Heer also unites with Z. Meekii some ovate emarginate 
leaves from the Dakota and Greenland strata, to which he 
formerly gave the names Phyllites obcordatus and Leguminosites 
Marcouanus, but it is by no means certain that they were borne 
by the same tree that carried the leaves called Liriodendron 
Meekit. Indeed the probabilities are against it since no inter- 
mediate forms have been found, and none of the panduriform 
leaves of L. Meekii have been obtained from Greenland, where 
obovate, entire or emarginate leaves similar to those given the 
above names do occur, and also many of the emarginate, oblong- 
ovoid or lanceolate leaves, which I have called Liriodendron sim- 
plex. 
Several additional species of Liriodendron are enumerated by 
Mr. Lesquereux among the fossil plants of the Dakota group, 
viz.: L. giganteum, Lesqx.; L. intermedium, Lesqx., (Cret. 
Flora, p. 93, Pl. XX., fig. 5; Pl. XXIL, fig. 2); L. acuminatum, 
Lesqx. ; L. cruciforme, Lesqx.; L. semt-alatum, Lesqx.; L. pin- 
