288 THE POTOMAC! OR YOU]NaBK MESOZJlO FLORA. 



with pretty sharply defined ultimate meshes, polygonal in shape, and vary- 

 ing in the number of sides from four to six. 



Localities : Fishing hut above Dutch Gap Canal ; Fredericksburg ; 

 Kankey's ; rare. 



The shape of these leaves is a good deal like that of Salix. The 

 midnerve is in size out of all proportion to the primary nerves sent off 

 from it. In its primary nerves and in the shape of the leaf the plant is a 

 good deal like Glossochlcumjs transnmtans Ettingshausen and Gardiner.^ The 

 resemblance in leaf-form and nervation to Persoonia moUis R. Brown is 

 strong. The affinities of the plants of this genus seem to be with the 

 Proteacece. 



ROGERSIA ANGUSTIFOLIA, sp. nov. 

 Plato CXLIII, Fig. 2; Plate CXLIX, Figs. 4, H; Plate C'L, Figs. 2-7. 



Leaves narrow, small, very elongate-oblong, narrowed gradually to 

 the base and apex, subacute, sometimes curved ensiform ; midnerve pro- 

 portionally very strong, with a thick petiole ; lateral or primary nerves 

 ver}^ slender, going off at an acute angle and arching up towards the sum- 

 mit, forming more or less persistent nerves approximately parallel with the 

 margin, and having a flexuous course. They send off very obliquely slen- 

 der lateral nerves, which anastomose with the adjacent ones, and form 

 irregular, elongate, polygonal meshes, with their longer dimensions directed 

 upwards. The latter, by splitting up into ultimate nerves, form an irreg- 

 ular, lax, ultimate net-work. 



Locality : Fredericksburg. 



This is the most common angiosperm at Fredericksburg, and it is 

 rather abundant there. It has leaves shaped much like some forms of 

 Salix, but the nervation is different. The midnerve is remarkable for its 

 great proportional strength. The nervation is usually so fine that even 

 the primaiy nerves are seen with difficulty. The leaf-substance seems to 

 have been thick and the epidermis firm and durable, so that the leaves are 

 generally well preserved. 



In the shape and nervation of the leaves this plant may be compared 

 with Persoonia mollis R. Brown. 



^ British Eocene Flora, vol. 1, PI. Ill, Fig. 3. 



