OLDER POTOMAC OF VIRGINIA AND MARYLAND. 497 



this species and M. virginiensis. The size of the leaves varies somewhat. 

 An average size is represented in PL CIX, Fig. 2, which gives a nearly 

 complete leaf with the basal part well preserved. This was probably 

 a leaf not quite 6 cm. wide and a little more than 5 cm. long. This is 

 probably a leaf not of normal shape, for the transverse diameter in these 

 leaves was probably greater than the vertical, giving a subreniform 

 shape. Professor Ward has written on the label of another specimen 

 of Menispermites in the Mount Vernon collections the name M. reni- 

 formis Dn. This too is probably M. tenuinervis, but it was a leaf above 

 the normal size, as it was probably about 7 cm. in its transverse and 

 greater diameter. This leaf is represented in PI. CIX, Fig. 3. 



The material available for description in Monograph XV did not 

 permit a full determination of the plant. We may, with the help of 

 the Mount Vernon specimens, add the following to its description: 



The leaves were mostly small, rotundate, or subreniform in shape, 

 with the transverse diameter the greater, attaining a maximum of 7 cm. 

 The margin was entire or slightly undulate. The texture was thin. 

 The nerves of all orders are slender. The divergence of the principal 

 nerves takes place from a point within the lamina of the leaf, but nearer 

 the base than in the leaf of M. virginiensis. The general plan of the 

 nervation and the mode of its division are similar to those points in 

 M. virginiensis. 



PiNUs VERNONENsis Ward n. sp.« 

 PI. CIX, Figs. 4-6. 



A single specimen of a small winged seed was obtained in the Mount 

 Vernon collections. It was named by Professor Ward, on the label, Pinus 

 vernonensis, but no description was given. It does not seem to l^e the 

 same seed as P. schista. It is, in the seed proper, of about the same shape 



n Three winged seeds occur in tlie collections, all collected on November 6, 1892, at the Mount Vernon 

 locality, two of them in counterparts, which I had named as above before sending the collections to Professor 

 Fontaine. He found only two of these, one of which he was disposed to identify with the species from Hosiers 

 Bluff (see p. 530), but remarked that the wing was not cleft, which is the leading character of that species. 

 The other he labeled with the name I had given it. I can not see that these seeds differ specifically and will, 

 therefore, include them all under this species, which has the following character: 



Seeds small, 12 mm. long, the wing 9 mm. long, 5 mm. wide above the middle, rounded at the apex, nar- 

 rowing toward the point of attachment, the sides unequally curved, finely striate; the seed proper 5 mm. 

 long by 3 mm. wide. — L. F. W. 



MON XLVIII — 05 32 



