314 THE POTOMAC OR YOUNGER MESOZOIC FLORA. 



STERCULIA L. 



A good many of the leaves found in the Potomac flora appear to liave 

 some affinity with StercuJia, but only one species seems to be near enough 

 to the genus to justify its being placed in it. 



Steeculia elegans, sp. nov. 



Plate CLVII, Fig. 2; Plate CLVIII, Figs. 2, 3. 



Leaves paliiiately tripartite, the middle lobe largest, subrhombic in 

 shape and acute ; lateral lobes elliptical, acute, slightly curved upwards, 

 with the lower margin towards the base more convex than the upper, so as 

 to give the basal outline of the leaf a subcordate shape; a strong midnerve 

 runs through the middle of each lobe, the tliree radiating from the base 

 of the leaf; subordinate nervation not seen. 



Locality : Deep Bottom ; not very rare. 



These leaves vary a good deal in size. The base of the leaf has the 

 outline of some Sassafras. PI. CLVII, Fig. 2, is a restoration of the leaf 



ARALTA L. 



The genus AraUa, like Sterculia, plays a ver}^ unimportant part in the 

 Potomac flora, having, if present at all, only one very doubtful species. 



Aralia dubia, sp. nov. 



Plate CLVII, Figs. 1, 7. 



Leaf-substance thick ; shape of leaf not made out ; leaf divided for 

 some distance down into oblong-elliptical lobes, which at tip are subacute 

 and sometimes prolonged into a mucronate point, each lobe having one or 

 two midnerves, and from these lateral nerves go off obliquely and remotely 

 that arch strongly up towards the tips of the lobes, following the margin 

 in their upper course ; ultimate nervation not seen. 



Locality: Deep Bottom ; rare. 



PI. CLVII, Fig. 1, seems to represent the upper part of a lobe. In 

 Fig. 7 the leaf seems to have been divided into four or five lobes. The 

 right-hand segment, containing two midnerves, seems to be the central lobe. 



