36 The Lower Cretaceous Deposits op Maryland 



1859, and more fully described by Professor Joseph Leidy in 1865. From 

 the same bed which yielded the tooth Tyson records '' a new genus of 

 Cycas of large dimensions/' " silicified coniferous wood/' and " lignites 

 (coniferous)." In his next report, published in 1863, Tyson discusses 

 these iron-ore clays and says he is disposed to place them as low as the 

 oolitic, which view is concurred in by Agassiz, to whom he had showed 

 a photograph of the cycad trunk. Tyson found a number of these cycad 

 trunks and sent pictures of them to various geologists. They are men- 

 tioned by Professor Dana in the first edition of his Manual, with the 

 comment that P. T. Tyson observes that they may be Upper Jurassic. 

 One trunk was presented to Professor Dawson and is still at Montreal, 

 another was presented to Professor Marsh and is now in the Yale College 

 collection, while a third turned up recently at the South Carolina Col- 

 lege at Columbia, probably a gift by Tyson to Professor Le Conte, who 

 at that time was located at Columbia. The others were for a long time 

 in the possession of the Maryland Academy of Sciences, which institution 

 eventually turned them over to the Johns Hopkins University where they 

 are at the present time. Professor Dawson sent one of Tyson's photo- 

 graphs to Carruthers, who refers to it in a postscript to his memoir 

 " On Fossil Cycadean Stems from the Secondary Eocks of Britain/' pub- 

 lished in 1870. 



Professor Cope in a paper read before the Philadelphia Academy in 

 1868, sketches the geology of the Cretaceous as developed from ISTew 

 Jersey to Virginia, mentioning the cycadaceous plants of Tyson, and also 

 referring to the clays along the Eappahannock from which Professor 

 Uhler has obtained the " remains of some six species of plants, in beau- 

 tiful preservation, of the order Cyeadacese ?, Gnetacege, and Filices." 

 This was probably the Fredericksburg plant locality which afterward re- 

 warded Professor Fontaine's efforts with such a great variety of speci- 

 mens. Professor Cope states that it is extremely probable that these 

 Virginia beds are the continuation of those of Maryland and Alexandria, 

 and he proceeds to sketch the conditions of deposition comparing them 

 to the conditions which prevailed to the westward in Triassic times. He 

 says further : " The age is therefore probably truly Wealden or Neo- 

 comian." 



