Maryland Geological Survey 493 



INCERTAE SEDIS 



Genus HEDERAEPHYLLUM Fontaine 

 [Mon. U. S. Geol. Survey, vol. xv, 1890, p. 323] 



This genus received the following brief diagnosis by its describer: 



"Leaves of rather small size, rotund ate in form, with nerves radiating 

 from the base of the leaf, the middle one being the strongest; petioles 

 long and moderately strong; leaf substance thick/' 



While the foregoing would apply to a score of genera of dicotyledonous 

 leaves it is difficult to frame a proper diagnosis for such fragmentary 

 remains which are described in more detail under the single species. A 

 second species was described by Fontaine which proved upon careful 

 comparison to be referable to Aralicepliyllum. 



The remains constitute an unimportant element in the flora of the 

 Patapsco formation and show no especial affinity with the modern species 

 of Hedera, the supposed resemblance to which was the occasion for the 

 name given to them. 



Heder^phtllum dentatum (Fontaine) Berry 



Protecephyllum dentatum Fontaine, 1890, Mon. U. S. Geol. Survey, vol. xv, 

 1889, p. 286, pi. clvi, fig. 7; pi. clxxii, figs. 1, 4; pi. clxxiii, figs. 12, 14. 



HederwpJiyllum crenulatum Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 

 1889, p. 324, pi. clxii, fig. 3. 



Protecephyllum dentatum Fontaine, 1906, in Ward, Mon. U. S. Geol. Surv., 

 vol. xlviii, 1905, p. 563, pi. cxviii, figs. 3, 4. 



Description. — Leaves ovate to orbicular in general outline, 5 cm. to 

 6 cm. in length by 2 cm. to 6 cm. in greatest width. Apex obtusely 

 rounded. Base usually subcordate. Margin varying from crenulate 

 to dentate. Petiole stout. Midrib slender and but slightly differentiated. 

 Primaries slender, four to six in number, diverging at narrow angles 

 from the apex of the petiole, somewhat flexuous and sooner or later 

 anastomosing by their dichotomous forking to produce large elongate 

 subrhombic meshes. Secondaries few, ultimately craspedodrome. Texture 

 coriaceous. 



This species in the condition of numerous imperfect and illy-defined 

 fragments is common in the Federal Hill beds and occurs sparingly 



