310 THE POTOMAC OR YOUNGER MESOZOIC FLORA, 



size, as indicated by PI. CLXXTII, Fig. 2. That shown in Fig. 5 of the 

 same plate seems in lobing and nervation somewhat different from the 

 others. 



MYRICA L. 



The genus Myrica is represented in the Potomac flora by only one 

 doubtful species, and this is exceedingly rare. 



Myeica Brookensis, sp. nov. 



Plate CL, Fig. 11 ; Plate CLVI, Fig. 10. 



Leaves quite small, elliptical in outline, acute, naiTOwed to the base, 

 pinnate, margins beginning a little above the base, serrated with small 

 acute teeth directed forwards; petiole quite short; midrib rather stout at 

 base, much and rapidly attenuated above ; primary nerves slender, leaving 

 the midrib obliquely curving upwards and following the margins for some 

 distance, connected with one another by nerves that go off nearly at right 

 angles ; ultimate nerves not seen. 



Locality: 72d mile-post, near Brooke; very rare. 



BOMBAX L. 



This genus also has one doubtful and very sparingly developed 

 species. The leaf placed in this genus occurs very rarely. 



BoMBAX ViRGINIENSIS, Sp. nov. 



Plate CLI, Fig. 4. 



Leaf small, oblong, tip not seen, elliptically rounded at base ; mid- 

 nerve slender ; petiole long, slender, and curved to one side, both distinct 

 and prominent ; leaf-substance thick and leathery ; lateral primary nerves 

 going off nearly at right angles, forking about midway in the leaf, sending 

 nerves backwards and forwards, which unite to form pentagonal spaces, 

 from the angles of which branches go off nearly perpendicularly towards 

 the margins. 



