OLDER POTOMAC OF VIRGINIA AND MARYLAND. 513 



Myrica brookensis Fontaine 



PI. CVIII, Fig. 8. 



1889. Myrica hrooJcensis Font. : Potomac Flora (Monogr. U. S. Geol. Surv., Vol. XV), 

 p. .310. pi. cl, fig. 11; pi. clvi, figs. 10, 10a. 



This species does not seem to have been abundant, as only 2 speci- 

 mens were obtained. One of these is a fragment of a leaf and the other a 

 nearly entire leaf. This latter is a small leaf with serrate margins. It is 

 given in PI. CVIII, Fig. 8. It has the nervation of Myrica brookensis and 

 is most like the form described in Monograph XV, but the leaf is somewhat 

 wider. 



QUERCOPHYLLUM CHINKAPINENSE Ward n. Sp. 



Pi. CXII, Figs. 3, 4. 



Fourteen specimens of what seems to be a new species of Quercophyl- 

 lum were found at the exposure No. 1. The specific name proposed for 

 this by Professor Ward, chinkapinense , is derived from the locahty. The 

 best specimens are the two leaves given in PI. CXII, Figs. 3, 4. Fig. 3 

 gives a portion of a narrowly elliptical leaf with a very slender midrib . This 

 sends off, very obhquely, slender secondary nerves that curve forward 

 toward the tip of the leaf and nearly reach the margin. The tertiary 

 nerves can not be made out distinctly. They seem to have the indefinite 

 lax nature that is so characteristic of the dicotyledons of the lowest 

 Potomac. This leaf has something of the aspect of a Rogersia, but the 

 secondary nerves are stronger and more definite in their course. Fig. 4 

 represents an entire leaf well preserved. This has the petiole and all of 

 the leaf except the extreme tip. The end of the leaf is serrate for a short 

 distance with teeth similar to the other species of this genus found in the 

 Lower Potomac. This specimen gives an idea of the shape of the leaf. It 

 is elliptical in form and is narrowed suddenly near the base. 



Thyesopteris crassinervis Fontaine. 



PL CXII, Figs. 5, 6. 



1889. Thyrsopteris crassinervis Font.: Potomac Flora (Monogr. U. S. Geol. Surv., 

 Vol. XV), p. 130, pi. xli, figs. 1, la, lb, 2, 2a, 2b, 3, 3a, 3b. 



This plant shows 9 specimens, and some of them are of larger size than 

 is common in the ferns found at this locality. The best specimen is a con- 



MON XLVIII^)5 33 



