496 MESOZOIC FLORAS OF UNITED STATES. 



Mexispermitks TKXuixERVis Fontaine. 

 ?1. ('IX. FiiTs. 2, :5. 



18S9. Menispermites temiinervhs Font.: Potomac Flora fMonoer. U. S. Cool. Snrv., 



Vol. XV), p. 322, pi. clxxii. fijr. S. 

 1895. Menispermites rirginiensis Font. Ward: Fit'tconlli Ann. Kep. U. S. Geol. 



Surv., 1893-94, p. 360," pi. iv. (!<;. 7. 



Xo fewer than 31 specimens I'eferable to this species occur in the 

 collections from the Mount Vernon beds. All but three are from the 

 Mount \'ernon locality, but these three were found at White House Bluff. 

 These specimens represent a plant which appears to I)e specifically dif- 

 ferent from .1/. virginiensis. This latter is not rare in the collections, 

 and differs in several important points from the plant now in question. 

 As given in Monograph XV, a small Menispermites, described as M. 

 tcmiinervis'' was found very rarely on Jackson, formerly Belt street, 

 Baltimore, Md. The specimens found in Baltimore were very rare, and 

 mostly small fragments. The most complete leaf, given in fig. 8, showed 

 fully a portion of the three primary nerves. The size of the leaves and 

 the delicate nervation of the Mount Vernon specimens are points that 

 agree with the Baltimore plant, and make it probable that the specimens 

 belong to M. tcnninervis. These leaves differ markedly from those of 

 M. virginiensis, since they are generally much smaller. The nervation 

 is also much more delicate. This was probably the case with the Bal- 

 timore plant, and hence the difficulty of seeing its nervation. The fine 

 clay of the Mount Vernon localities is exceptionally well fitted to show 

 delicate details, otherwise the minor nervation would probably l^e 

 inconspicuous in these specimens also. The small leaf given as M. vir- 

 giniensis in pi. iv., fig. 7,' of Professor Ward's Mount Vernon flora'' is 

 probably this species. The contrast between this leaf and the one rep- 

 resented in fig. 8 of the same plate illustrates well the difference between 



oFrora the statement here made it seems that Professor Fontaine, to whom some of the Mount Vernon 

 material was submitted at that time, himself referred both those leaves to his M . rirginiensis. The dillorence 

 may not l)e specific. — L. F. W. 



f" Monograph XV, p. .322, pi. clxxii, fig. S. 



|"The Potomac formation: Fifteenth Ann. Itep. U. S. Geol. Surv., 189.5, pi. iv, fig. 7. 



''Tlirougli inadvertence the counterpart of this specimen was drawn for this paper, and is represented 

 on PI. CIX, Fig. 2. In view of the fact that Professor Fontaine refers this specimen to M. leniiinenis it may 

 be well to retain the figure. It shows the lower side of the leaf, where the raised nerves are more distinct than 

 they are on the upper side. — L. F. \V. 



