124 L. F. Ward — Evidence of the Fossil Plants 



Sjjhenole r pidi%im Kurrianum Heer, and S. Sternbergianum 

 (Dunk.) Heer, in all seven identical species. Nine other 

 Potomac species have allies in the Wealden of G-errnany. 



Four Potomac species are allied to plants found in Japan, in 

 deposits usually regarded as Jurassic, but which may be lower 

 Cretaceous. 



Forms of Pecopleris Whitbiensis found by Trautschold at 

 Klin near Moscow closely resemble CladojMebis falcata and 

 G. oblongifolia of the Potomac flora. Professor Fontaine, 

 following Schenk, regards this deposit as Wealden. 



Neocomian. — The principal beds recognized as belonging to 

 this series containing Potomac types, are those of the Valle de 

 Lobos and of Almargem in Portugal, whose flora was elabo- 

 rated by Heer in 1881. Four of the Wealden species found 

 in the Potomac and already enumerated recur here, leading to 

 the strong suspicion that the Portuguese beds may also be of 

 Wealden age. One of these (Sphenolepidium Sternbergianum) 

 is also found in alleged Neocomian strata near Oerlinghausen 

 in Westphalia. 



Professor Fontaine's Taxodium Virginicum appears to be 

 allied to T. (Glyptoslrobus) Groenlandicum of Heer, which 

 occurs in the Kootanie beds of the British Northwest Terri- 

 tory, correlated by the Canadian geologists with the Neoco- 

 mian, and Araucarites Yivginicus resembles Araucaria ere- 

 tacea Brongn. from Nogent-le-Potrou in France, which is 

 thought to be not lower than Cretaceous. 



There are therefore four species common to Neocomian and 

 Potomac strata, and seven others which are related more or 

 less closely. 



Urgonian — To this epoch are referred the Kome beds of 

 Greenland, and the Wernsdorf beds, lying chiefly in Austrian 

 Silesia. The rich flora of the former was elaborated by Heer, 

 and it will be remembered that it was here that a single dico- 

 tyledonous plant, Pojmlus primaeva Heer, was found which, 

 if no mistake was made, was the most ancient plant belonging 

 to that subclass that had been found prior to the opening up of 

 the Fredericksburg beds. This species does not occur in the 

 Potomac flora, but Ave other Kome species do occur there, 

 viz : Gleichenia Nordenski'oldi Heer. (though this is some- 

 what doubtful), Sequoia Reichenbachi (Gein.) Heer, S. am- 

 bigua Heer, S. rigida Heer, and S. gracilis Heer. Besides 

 these identical species there are eleven Potomac plants that 

 bear more or less resemblance to those of Kome. 



The Wernsdorf beds contain two species found in Potomac 

 strata, one of which, Dioonites Buchianus Schimper, does not 

 occur at Kome, and there are four other species of Potomac 



