OLDER POTOMAC OF VIRGINIA AND MARYLAND. 507 



given in that figure. The original margin of the leaf is retained only in 

 the left-hand upper portion. Here there is an indication of a rather 

 shallow lobe, in which ends a secondary nerve that is considerably 

 stronger than any of the others sent off from the midrib. The latter is 

 rather slender for a leaf of this size and ends in what appears to be a 

 terminal lobe, which is only partiall,y preserved. The right-hand margin 

 of the leaf is not preserved, so that if a lobe once existed on that side it is 

 not visible now. That none such existed is indicated by the fact that 

 no strong secondary nerve is sent off on that side corresponding to the 

 one on the left-hand side, which ends in the lateral lobe. The sinus made 

 by the left lobe' with the terminal lobe is more open than that found in 

 S. bilobatwm figured on pi. clxiv of Monograph XV, and indeed it is 

 more like that of a Liriodendron. The specimen is No. 8437 of the 

 Maryland Geological Survey. 



Sequoia ? inferna Ward nom nov." 



1889. Sequoia species ? Font. : Potomac Flora (Monogr. U. S. Geol. Surv., Vol. XV), 

 p. 248, pi. cxvi, fig. 7; pi. cxxxii, figs. 2, 5, 6. 



There are in the collection two dissected cones with a few scales 

 attached that exactly resemble the specimens described in Monograph 

 XV as "Sequoia species ? " and figured on pi. cxxxii, in figs. 2, 5, 6. 

 This is a very well characterized cone, easily distinguished from any other. 

 It is known to occur only in the Aquia Creek beds, and although it can not 

 be assigned to any species founded on leafy branches, and hence was left 

 undetermined, it is none the less of value in indicating the age of the 

 strata containing it. The specimens bear the numbers M. G. S., 8 54, 

 8465. 



Sphenolepidutm Steenbergianum densifolium Fontaine. 



PI. CXII, Fig. 1. 



1889. Sphenolepidium Sternhergianum densifolium Font.: Potomac Flora (Monogr. 

 U. S. Geol. Surv., Vol. XV), p. 261, pi. cxviii, fig. 7; pi. cxxi, figs. 5, 5a, 5b, 

 7, 7a, 9, 9a; pi. cxxv, figs. 2, 2a, pi. cxxix, fig. 3; pi. cxxx, figs. 1, la; pi. 

 cxxxi, figs. 1, la-lc, 3, 3a; pi. cxxxu, figs. 4, 4a. 



« These, as Professor Fontaine says, are well-characterized cones and scales, recognizable wherever found, 

 and therefore of diagnostic value in determining age. The fact that they can not be identified with species 

 known by the foliage does not seem to be a sufficient reason for not assigning to them a specific name. The 

 name adopted relates to the locality now being treated. — L. F. W. 



