1902] NOTES ON THE PIIYLOGENY OF LIRIODENDKON 49 



imply that the diverse forms are found in the Cretaceous simply 

 because the conditions were favorable for the fossilization of the 

 abnormal forms. 



In opposition to the foregoing, our reasons for considering 

 the various described species valid are: 



I. 



The majority of abnormal leaf forms in the living L. Tulip' 

 ifera are young leaves, and they would not be likely to become 

 detached and preserved as fossils. 



2. We have every reason to expect numerous species in a 

 tree ranging over so many lands (Europe, Asia, America), and 



throughout such a long period of time (Lower Cretaceous to the 

 present). 



3. The Cretaceous was a period of development and variation 

 in the dicotyledons. 



4- Ontogeny, or the individual development of modern types, 

 more or less parallels their phylogeny,or actual ancestry. Gen- 

 erally speaking, this applies to all animals and plants, 



5. The weight of authority is all on the side of many species, 

 Lesquereux^ going so far as to say **from the remarkable diver- 

 sity of characters seen in the leaves of Liriodendron described in 

 this volume, I believe that no botanist would be disposed to 

 consider them as mere varieties of the original obovate simple 

 leaves.'' In criticising Holm's paper on Liriodendron, Professor 

 Lester F, Ward^'says "modern forms more likely represent the 

 phylogenetic stages through which the present living species has 

 passed." This is the view held b}- all, so far as I know, of the 

 various authors who have written of this group, as Newberry, 

 Lesquereux, Hollick, etc., in this country, and Heer, Ettings- 

 hausen, Unger, Saporta, Velenovsky, Massalongo, etc., abroad. 



6. If stipules were present — and they must have been, since 

 Linophyllum populoides of the Dakota and Liriodendron alatum of 

 the Laramie show their incipient stages — they should occur as 

 fossils, either separately, if we assume them to have been fuga- 

 cious, as they are at the present time, or attached to the peti- 

 oles of the fossil leaves, if they were persistent. 



* Flora of Dakota group, pp. 205, 206. ^ Am. Jour. Sci. III. 40 : 422. 1890. 



Mo, Bot. Garaeri 



1£03. 



