286 JR. L. Hoodie — American Jurassic Frog. 



Art. XXVII. — An American Jurassic Frog ; by Hoy L. 



Moodie. 



The remains of Amphibia between the close of the Triassic 

 and the opening of the Tertiary are among the rarest if not 

 the rarest of fossil vertebrates. One can almost count on the 

 fingers of one hand the species of Amphibia known in the post- 

 Triassic, pre-Tertiary times. These are : Hylceobatrachus 

 croyii Dollo of the Belgian Wealden ; Scapherpeton excisum 

 Cope, S. favosum Cope, S. laticolle Cope, S. tectum Cope ; 

 Hcmitrypus jordanianus Cope, all from the upper Cretaceous 

 (Laramie) of Montana, and Canada. So far as I know, other 

 amphibian remains have not been described elsewhere from the 

 formations mentioned. 



Professor Marsh, in 1887, referred to some amphibian bones 

 from the Como Beds* of Wyoming, calling attention to the 

 previous mention of the species, f Again, in discussing the 

 fauna of the Denver Basin, \ he mentioned the amphibian where 

 he says : "A batrachian (Eobatrachus agiiis) and a pecu- 

 liar fish ( Ceratodus guntheri) have likewise been found in this 

 horizon. " The material has not been fully described, since all 

 Professor Marsh's mention of them in 1887 is as follows : 

 " More recently, various bones of small anourous amphibians 

 ( Eobatrachus agiiis) have been found, the first detected in 

 any Mesozoic formation. " 



Thus it is that, up to the present, the Eobatrachus agiiis of 

 Marsh has been a nomen nudum, and the discovery has been 

 discredited. Recently through the kindness of Professors 

 Schuchert and Lull of Yale University I have been permitted to 

 examine the remains referred to by Professor Marsh, and find 

 on examination that they are undoubted remains of Salientia, 

 and of the modern type. There is no distinction, so far as I 

 am able to observe by the most careful comparisons, between 

 this Jurassic frog and the frogs and' toads which are around 

 us to-day. This is the more remarkable on account of the great 

 age of the species. The Salientia have been suggested in the 

 Pennsylvanian by Pelion lyelli Wyman, from the Coal Measures 

 of Ohio, and attention has been directed to the salientian char- 

 acters of the species by various writers. No intermediate forms 

 are known and both the Jurassic and the Carboniferous forms 

 are far too indefinite for any conclusions to be based on them 

 as to phylogenetic descent. The transition took place in the 

 Permian or late Pennsylvanian since this species Eobatrachus 

 agiiis Marsh has every identical character of the modern Sali- 

 entia. The origin of the Salientia, like that of nearly all of 



*This Journal (3), xxxiii, p. 328, 1887. 



•fProc. Brit. Assn. Science, Aberdeen Meeting, 1885, p. 1033. 



% Monograph U. S. G. S., xxvii, p. 508, 1897. 



