DESCRIPTION OF THE SPECIES. 221 



genus JEchinosfrohus. Ag-ain, in many points tliey are a good deal like 

 Saporta's genus rahcocyjxiris, but in this latter the leaves are decussate, 

 while in the Potomac plants they are more numerous and spirally arranged. 

 It is possible that the Potomae fossils belong to a generalized type allied 

 to Erhinosfrobiis and Falieorijpnrls, but standing nearest to Bt achy yhijU urn 

 It seems best to place them provisionally in this last genus. 



Bracuyphyllum crassicaule, sp. uov. 



Plate C, Fig. 4; Plate CIX, Figs. 1-7; Plato CX, Figs. l-:i ; Plate CXI, Figs, ti, 7; Plate CXII, Figs. 

 C.-8; Plate CLXVIII, Fig. 9. 



Trees with large branches, irregularly pinnate ; on the penultimate 

 twigs the ultimate branches lower and next to the main branch sulxlivide 

 pinnately into branches ; those higher are uubranched and simj)le ; ultimate 

 branches vary in numbers and closeness, sometimes few and remote, and 

 again crowded, contiguous, almost touching; towards the .summit of the 

 penultimate branches the ultimate ones become much crowded and grow 

 gradually shorter, are cylindrical, and taper gradually to an obtuse point ; 

 leaf-scars of young leaves elliptical in shape, slightly prolonged in the 

 direction of the axes of the stems, and such leaves seem to have been 

 fleshy, slightly convex, and with a free tip sliglitly keeled in the ujjper 

 half; with age the leaves become broader and uiore convex, being broadly 

 elliptical, almost circular, and they leave similar scars after their fall ; 

 when crowded and dilated wuth age the leaves and leaf-scars are sub- 

 rhombic or rhombic in shape ; the surface of the leaves, which is very rarely 

 preserved, shows fine tubercles or dots, arranged in curving lines parallel 

 to their margins and converging towards their tips; cones small, globular, 

 or subelliptical in shape, attached laterally to the penultimate twigs, taking 

 the place of idtimate branches; scales numerous, spirallv arranged, touch- 

 ing, shape not made out, but probably with age rhombic and ])olygoiial. 



Localities : Entrance to Trent's Reach ; I'lA mile-post, near Brooke ; 

 fishing hut above Dutch Gap Canal. 



Fragments of tliis plant are abundant at the first-named locality in the 

 same stratum with Frcndopsis parceramosa, etc., and are rather rare at the 

 "other localities. Most of the specimens showing scars of leaves occur here. 



