COPE ON GEOLOGY AND VERTEBRATE FOSSILS. 577 



Carboniferous Biplodus. In the Trias, we have the marine Muschel- 

 kalk, followed by the elevation which inclosed the estuaries and 

 lakes of the Keuper, with its land fauna of Saurians. At the A 

 summit of the Jurassic stands the Wealden, which is attached to the ; 

 epochs below it by modern paleontologists, and is not arranged with 

 the Cretaceous above it. It is in harmony with these views of Euro- 

 pean paleontologists that the Lignitic beds should be placed at the 

 summit of the Cretaceous formation, within its boundaries, as the Verte- 

 brate paleontology so strongly indicates. Although more extensively , 

 developed in the United States than in Europe, this formation is not 

 wanting in the latter region ; it occurs there in Provence, under the 

 Garumnien system of M. Leymerie. In this bed are found JDinosauria 

 [Rhahdodonpriscum)^ Crocodilia, and Tortoises near to JEniys and TrionyXy 

 a Eeptile fauna with the fades of that of the Judith River beds. Professor 

 Gervais remarks of this fauna that it also occurs in the Gosau Basin, 

 near Xeustadt, near Vienna, Austria, and that the Iguanodon suessii 

 Bunzel, found there, is identical with the Ehahdodon priscum.* He also 

 informs us t that " M. Matheron, of Marseilles, has recognized the neces- 

 sity of associating with the superior part of the Cretaceous formation cer- 

 tain strata which other authors had at first regarded as belonging to the 

 Tertiary period". These beds are thus alluded to by Count Gaston de 

 Saporta in a letter to Dr. Hayden :| — " Nevertheless, in Provence even, 

 and quite at Aix, we have a small agglomeration of what is known un- 

 der the name of lignite of Eelveau, which my friend Matheron has de- 

 termined as the equivalent of the fresh- water Upper Cretaceous forma- 

 tion (Santonien), which passes by degrees in its upper x^art into strata 

 incontestably of Tertiary age." 



I will remark in conclusion, that it is probable that the Lignitic for- 

 mation will come to be regarded as a primary division of the Cretaceous, 

 and equivalent as a whole to all or part of the older marine series. It 

 will include as subdivisions the Judith Eiver and Fort Union epochs, 

 as already defined by Mr. Meek from the Invertebrate fossils,§ and prob- 

 ably^ the Laramie or Bitter Creek epochs as distinct from them. 



2. — VERTEBRATA FROM THE NIOBRARA CRETACEOUS. 



ELASMOSAURUS Cope. 



Proc. Acad. Pbila., 1868, p. 92; Ext. Batr. and Rept. North America, 18G9, p. 44. 



The addition of a third species to this genus renders it proper to fur- 

 nish a table of the more prominent characters which distinguish them. 

 This can be more readily done, since I have come into possession of the 



* If this be true, Rhabdodon is distinct from Cionodon or Dichnius. 

 t Comptes Rendiis, January 22, 1877. 

 i American Naturalist, 1877, March, p. 186. 



^ Report United States Geological Survey Territories, Invertebrata, by F. B. Meek, 

 p. xlvii. 



