274 THE POTOMAC OE YOUNGER MESOZOIC FLORA, 



UNDETERMINED PLANTS. 



The plants next following do not possess characters that place them 

 definitely in any particular group of vegetable forms. I give figures of 

 them, as they seem to be worthy of notice, and, so far as can be made out, 

 they are different from any of the fossils described under other heads in 

 this memoir. 



Macrospores % sp. 



Plate CXXXVI, Fig. 1. 



At the fishing hut above Dutch Gap Canal we occasionally, but 

 rarely, find, on certain thin layers of fissile, very fine-grained clay, a num- 

 ber of minute circular markings confusedly associated together. As seen 

 under a lens, they are in the form of a circular raised ring, in the center of 

 which is a minute knob. They occur also in the red clay ball in the banks 

 of Dutch Gap Canal. 



Undetermined plant (a). 



Plate CXXXVI, Fig. 13. 



This peculiar stem is more like an Ephedra than any other plant 

 known to me. It has a number of long, slender, woody cylindrical stems, 

 which radiate from a common point. In several places they seem to be 

 jointed, but the jointing does not appear to be generally present. In sev- 

 eral there are scars, as if left by the detaching of twigs. The stems are 

 decorticated. 



Locality: Fredericksbui-g; only one specimen. 



Undetermined plant (6). 



Plate CXXXVI, Fig. 14. 



This plant is composed of a number of woody cylindrical twigs, that 

 branch in a dichotomous manner, and pursue an irregular, flexuous course. 

 In the irregular branching and flexuous character of the twigs it looks 

 more like a root than an aerial growth. 



Locality: Occurs in one specimen at Fredericksburg. 



