PLANT LOCALITIES. 31 



them, they mnj have been introduced into the somewhat h\ter material. I 

 call attention to tlii.s possibility because of the almost universal change of 

 wood to ligiiite in the lower Potomac clay. Silicified wood is rare in the 

 Potomac and occurs almost without exception in sand}- matter. 



According- to Mr. Tyson's notes, one of the trunks, but which it is, 

 impossible to sa}', was obtained from Dr. Jenkins's mine near Contee's sta- 

 tion, and the other from Mr. Emack. The latter was obtained from his 

 farm near Beltsville. It does not appear whether this was obtained from 

 an iron mine or was picked up on the surface. Presumably it was found 

 occurring- like the one ol)tained from Dr. Jenkins. The nse of the plural 

 by Mr. Tyson seems to imply this, for while both trunks were sent to 

 him by Dr. Jenkins, only one was found in his mine. The location of 

 Contee's station and that of Beltsville are given in the i)revious mention 

 of these trunks. 



In the excavation of the cla}' for iron various animal fossils have been 

 found. The ore-pits in the vicinity of Contee's ajtpear to have yielded 

 more of these than any others, and they would seem worthy of the notice 

 of collectors. Unfortunately little attention has been paid to the collec- 

 tion and preservation of these fossils. Most of the specimens have been 

 lost, and in the ca.se of the few that have been preserved nothing is known 

 of the pits yielding them or of the horizon on which the}- were found. 

 Some of these fossils are preserved in the ^Museum of the Maryland 

 Academy of Sciences. In the main they have not been examined by 

 scientific experts, and hence, if proved to come from the Variegated Clays, 

 they can not be used in determining its age. The fact noted by Tyson 

 that some of them occurred near a large undisturbed lignite tree makes 

 it not altogether certain that they all occur in the true Variegated 

 Clays/ 



"^I'lie amount of material obtained from the different plant localities and 

 worked over is very considerable. The area over which these localities 

 are distributed is large enough to 3-ield a fair representation of the f^ora 



'Since this was written Professor MiirsU li.as obtained a largo uunibor of Dinosaurian bones from 

 this Variegated Clay gronp in Maryland. Re thinks they bclonj; fo Jurassic types. His discoveries 

 make it plain that the first discovered animal fossils come from the Variegated Clays. 



