DESCKIPTION OF THE SPECIES. 307 



wards, branching apparently in a dichotomous manner ; ultimate reticula- 

 tion njt seen; leaf-substance very tliin. 



Locality : Covington street, Baltimore ; very rare. 



Celastropiiyllum obovatum, sp. nov. 



Plato CLXXII, Figs. 9, 10. 



Leaf-substance very thin ; leaves small, rounded, and very obtuse at 

 summit, narrowed gradually to the base, obovate in shape ; midnerve strong 

 at base, much attenuated towards the sununit ; lateral nerves very slender, 

 going off very obliquely and curving around towards the summit, flexuous 

 in their course and sending off obliquely branches which connect either 

 with other branches or with the primaries, forming large, elongate, subrhom- 

 bic meshes ; ultimate nervation not seen. 



Localities : Belt and Covington streets, Baltimore ; not unconnnon. 



This leaf is much like that of Emnymus frUjidus. It is also like that 

 of Celastnis obovatus, but the nervation is different. 



QUERCOPHYLLUM, gen. nov. 



Leaves small, wedge-shaped at base ; leaf-substance thick, with strong 

 ovate teeth directed forwards ; midnerve strong at base, rapidly attenuated 

 above ; lateral or primary nerves sometimes slender, going off very obliquely 

 and curving forwards, forking dichotomously ; ultimate nervation not seen. 



The leaves placed in this genus, from their affinity with Qnercus, are 

 rare and unimportant, since they play but a very small part in the Potomac 

 flora. The amount of- material found is too small, and the degree of pres- 

 ervation too poor, to permit their character to be definitely fixed. 



QUERCOPHYLLUM GROSSEDENTATUM, Sp. UOV. 

 Plate CLVI, Fig. 0. 



Leaf small, entire shape not shown ; margin furnished with very large 

 ovate, acute, unequal teeth, that are turned upwards ; midnerve quite strong 

 towards the base, much attenuated above, and splitting up into the primary 

 nerves ; primary nerves subopposite, strong at base, forking dichotomously. 



Locality : 72d mile post, near Brooke ; found in only one specimen. 



