498 BROOKLYN BOTANIC GARDEN MEMOIRS 



existing Q. undulata, as he understood that species, in which were 

 comprised entire, frequently toothed, and very deeply lobed forms, 

 some of which he was disposed to segregate varietally as others have 

 done specifically, but all intergrading, as he saw it, as forms of one 

 single extremely polymorphic species (13). 



Similar polymorphism is shown by the many forms of associated 

 European Tertiary oak leaves studied by von Ettingshausen and 

 included in his conception of Q. palaeo-ilex. Guided by venation 

 studies, he was able to see in this species a foreshadowing of all of the 

 modern types of oak foliage (14). In the absence of other knowledge 

 than we now possess, I am disposed to think that in the holly-like form 

 we may see a starting point for the successive reevolution of the various 

 forms of leaf that Quercus has presented in the several geological ages, 

 and now presents. 



References 



1. An indispensable aid in locating first references to American 

 post-carboniferous fossil plants, in this as in other genera, is Professor 

 Knowlton's catalogue of Cretaceous and Tertiary plants, published as 

 Bulletin no. 152 of the United States Geological Surv^ey — though it 

 is now antiquated. 



2. Fruit of Q. consimilis and Q. paucidentata is figured by Hollick 

 in Monograph 35 of the U. S. Geological Survey, PI. 43. 



3. Nominal species of Quercus subsequently transferred to other 

 families than Fagaceae are Q. anceps Lesq. (Diospyros ambigiia), 

 Q. Benzoin Lesq. {Per sea Leconteana), Q. calif ornica Lesq. {Mespilo- 

 daphne pseiidoglauca), Q. chlorophylloides Knowlt. (Pisonia chloro- 

 phylloides), Q. elkoana Lesq. (Carpinus grandis), Q. Lyellii Lesq. 

 (Nectandra lancijolia) , Q. microdentata Hollick {Dillenites microdenta- 

 tus), Q. Mudgii Lesq. {Protophyllum Mudgii), Q. myrtifolia Lesq. 

 {Sophora Lesquereuxii) , Q. platania Lesq. {Platanus cordata), Q. 

 retracta Lesq. (Myrica bentonensis) , Q. Saffordi Lesq. {Banksia Saf- 

 Jordi), Q. semialata Lesq. {Anisophyllum semialatum) . 



4. Nominal North American species of Quercus subsequently 

 transferred to Dryophyllum are Q. crassinervis Lesq. {D. tennesseense) , 

 Q. gracilis Newb. {D. subfalcatum) , Q. Moorii Lesq. {D. Moorii). 



5. The following European fossil species of Quercus are now believed 

 to be represented by segregable American forms: Q. acrodon {Q. 

 Lesquereuxiana Knowlt.), Q. angustiloba {Q. prae-angustiloba Knowlt.), 

 Q. chlorophylla {Q. chlorophylloides Knowlt.), Q. furcinervis (Q. furci- 

 nervis americana Knowlt.), Q. Johnstrupii (Q. raritanensis Berry), 

 Q. Laharpi (Q. fraxinifolia Lesq.), Q. mediterranea {Q. peritula Cock.), 

 Q. pyrifolia {Q. florissantensis Cock.), Q. voyana (Q. distincta Lesq.). 



