OLDER POTOMAC OF VIRGINIA AND MARYLAND. 515 



always detached, it can not be determined with what plant they are con- 

 nected. This seed is shown natural size in PL CVIII, Fig. 9, and enlarged 

 two diameters in Fig. 10. It was collected on April 16, 1893. 



Sphenolepidium Steenbergianum DENSiFOLiUM Fontaine. 



PL CIX, Figs. 8, 9. 



1889. Sphenolepidium Sternbergianum densifolium Font. 



1889. Ament of conifer (f) sp.? Font.: Potomac Flora (Monogr. U. S. Geol. vSurv.,, 

 Vol. XV), p. 227, pi. cxxxvi, figs. 8, 8a. 



This plant is represented by 49 specimens, being portions of ultimate 

 twigs, seeds, and fragments of aments. The portions of twigs are all very 

 small. They belong to ultimate twigs. The small objects described in 

 Monograph XV, p. 227, pi. cxxxvi, fig. 8, as ament of conifer (/) sp.?,, 

 exactly resemble a number of fossils found at the second exposure, and they 

 are pretty certainly the same. One of these is shown in the specimen 

 figured in PL CIX, Fig. 8, to belong probably to the leafy twig of S. 

 Sternbergianum densifolium. The unattached aments are not rare. They 

 are all fragments. One of the most complete of these is about 7 mm. long 

 and not quite 2 mm. wide. The imprints on it indicate that it was 

 probably covered with minute, closely imbricated, chaffy scales. In 

 shape the scales were broadly elliptic and terminated in acute tips. This 

 is shown in Fig. 9. Both the specimens figured were collected on April 

 16, 1893. It is to be noted that such objects are abundant at the 72d 

 Milepost, where the leafy twigs of S. Sternbergianum densifolium are 

 common. 



Ament of a dicotyledon ? Fontaine. 



PL CVII, Fig. 11. 



A single specimen showing a fragment of what seems to be the ament 

 of some dicotyledon was found at locality No. 2. It is nearly entire. It 

 is cylindrical in form, and from the imprint left seems to have been 

 covered with elliptical scales that were rather thick in texture and imbri- 

 cated. PL CVII, Fig. 11, shows it. It was collected on April 16, 1893. 



The horizon of all the plants from Chinkapin Hollow is clearly that of 

 the Rappahannock series. There is no difference in age between those from 

 the two localities except the time required to deposit the intermediate 

 20 feet of homogeneous materials. 



