32 LEAVES OF LIRIODENDRON HOLM. 



ent from that of tbe true Liriodendron—le^yes of the same relative 

 shape. I am inclined to believe that the drawings have not been made 

 with sufficient care and that the leaves, merely in regard to the outUnes 

 alone, belonged to a large leaved Liriodendron. They may not rei)re- 

 seut a true species but may be considered as leaves of younger trees 

 of some species with which they have been found associated, for ex- 

 ample L. quercifolium. We should, then, have a better illustration of 

 one of the ancestors of the Tulip-tree, the typical form, represented by 

 L. quercifolium, a variety ^^ oblongifolium,^^ and finally the same kind 

 of variation in the foliage as has been described in our recent tree, rep- 

 resented by the form '■'■simplexy 



We have now regarded a series of fossil leaves which have been 

 identified as having belonged to species different from the recent, but it 

 seems, however, as if the true Liriodendron TuUpifera had existed be- 

 fore in the Pliocene formation. A few years ago some leaves of a Lirio- 

 dendron were discovered in the Altai Mountains, which have been de- 

 scribed by Schmalhauseu* as identica'l with our recent species, and a 

 figure of one of these leaves shows the superior margin with the shallow 

 notch and a lobe, just as it is in the typical form of X. TuUpifera. It is 

 a discovery of great interest, since there is but a very small difference 

 between this leaf and Liriodendron Procaccinii var. helvetica from the 

 Tertiary formation of Switzerland a:id Iceland. 



If we will now consider these fossil leaves by themselves we shall 

 see that the majority are lobed with acute or obtuse lobes and that 

 there is on the other hand a number of which the lobes were probably 

 ■wanting, as it seems according to the defective fossils, or the leaves 

 show a more or less obcordate shape. They may be arranged in three 

 groups according to these characters, namely : 

 I. Leaf lobed. 



A. Lobes acute. 



L, acuminatum Lesqx. 



L. cruciforme Lesqx. 



L. Gardneri Sap. 



L. intermedium Lesqx. 



L. oblongifolium Newb. 



L. pinnatijidum Lesqx. ? 



L. Procaccinii var. Helvetica Heer. 



L. Procaccinii var. acutiloia Massal. 



L. quercifolium Newb. 



L. TuUpifera L. 



B. Lobes obtuse. 



L. giganteum Lesqx. 



L. Meekii var. genuina Heef. 



L. Meekii var. primceva (Newb.) Heer. 



L. Procaccinii var. incisa Massal. 



L.' Procaccinii vav. obtusiloba j '^"f£',f^/^ | Massal. 



L. semialatum Lesqx. 



* Ueber tertiiere PUauzeu aus dem Thale des Flusscs Buchtorma am Fusse des 

 Altaigebirges. Pahcontographica, xxxiii, 1887. 



