B. L. Moodie — Fossil Frogs of North America. 531 



Art. XLY1II. — The Fossil Frogs of North America; by 

 Rot L. Moodie. 



The present review of the fossil frogs of North America is 

 intended to give all the available data regarding the geological 

 and geographical distribution of the Salientia in this continent. 



Frogs are of rare occurrence in all known geological forma- 

 tions and our knowledge of their ancestry and origin is very 

 uncertain. It is my intention to indicate, in this review, the pos- 

 sible presence of the Salientia in the Carboniferous of North 

 America and the possible derivation of the salientian Amphibia 

 from other of the Carboniferous land vertebrates. It is the 

 further purpose of this paper to call attention to the discovery 

 of true toads in the Pliocene of Kansas. This announcement 

 is based on remains collected by Mr. J. B. Hatcher in August, 

 September, October of 1884 near Long Island, Kansas. The 

 specimens have recently been sent me for study through the 

 kindness of Mr. Charles Gilmore of the United States National 

 Museum, to which institution the specimens belong. It is the 

 further purpose of this paper to publish figures of the only 

 known American Jurassic Frog, the Fobatrachus agilis of 

 Marsh. Professor Marsh has evidently intended to describe 

 and illustrate the Fobatrachus fully, for these drawings were 

 found among his effects in the National Museum. They are 

 here published as he left them. 



Remains of Salientia have been found in the following geo- 

 logical formations : Carboniferous (Middle Pennsylvania) (?) ; 

 Jurassic (Comanchean) Como Beds ; Upper Miocene (Pliocene); 

 Pleistocene. 



Peliox ltelli Wyman. 



This Carboniferous species has been very thoroughly treated 

 in the writer's forthcoming monograph of Carboniferous 

 Amphibia and a detailed description in this place is not needed. 

 The length of the vertebral column was probably considerable, 

 possessing an estimated number of 22 or 23 vertebrae. The 

 vertebral segments of all modern and fossil Salientia is nine, 

 but it is well known that the urostyle is a series of coossified 

 vertebrae. This anyone may demonstrate to his satisfaction 

 by the study of a tadpole cleared by the potash method as out- 

 lined by Professor Mall- and the writer. + The ossifications 

 in the urostyle are definitely segmental and young stages show 

 perichondral ossifications similar in many respects to the ossi- 

 fication of other vertebral centers. The whole subject, how- 

 ever, needs careful study, and these observations, while I 

 *Araer. Journ. Anat., 1906. f Amer. Journ. Anat., 1908. 



