R. L. Moodie — American Jurassic Frog. 287 



our great vertebrate groups, is still involved in mystery. The 

 mystery is so great that it leads some to doubt the validity of 

 the theory of evolution by gradual development. No distinct 

 ancestral forms are known for any of the Amphibia save the 

 Caudata. Smith Woodward has made the same statement in 

 regard to the fishes and has emphasized the importance of the 

 Mutation theory of DeVries as the paleontological record has 

 thus far been read. The record is however still imperfect. 



The present specimens seem to indicate a bufonid nature 

 for the species. In fact I think we Will be safe in locating 

 the species in the family Bufonidse and possibly even in the 

 genus Bufo. It is entirely too soon for the species to be cer- 

 tainly placed in Bufo, since such a determination will have to 

 await future discoveries of more complete material, especially 

 of the pectoral girdle and the skull. 



The reasons for placing the species in the Bufonidse are 

 simply on account of the well-developed condition of the lower 

 end of the humerus and its apparently calcified condition. 

 This is hardly more than an inference but it is an inference which 

 has long been justified in Paleontology. Certainly the ulno- 

 radial articular end of the humerus of Eobatrachus agilis is 

 not the same as that of the modern Rana pipiens, or Rana 

 catesbiana and it does resemble the epiphysial structures of cal- 

 cified cartilage described by Parsons for some of the toads. 



The specimens represent two individuals and by the follow- 

 ing parts : One specimen, a lower end of a left humerus, 

 somewhat smaller than the type ; the other or type humerus ; 

 the lower end of a tibio-fibula ; the entire left (?) femur; the 

 entire right ilium, all, apparently, of a single individual except- 

 ing the humerus first referred to, which indicates a second 

 frog though possibly of the same species. All of the speci- 

 mens are from Quarry 9 of the Como Bluff in Wyoming. 



The humerus (No. 1862 Yale University Museum) of the 

 type as above stated is represented by the lower end only, this 

 portion measuring 6 mm in length, by 2 mm in distal width, by 

 slightly more than one half a millimeter in shaft diameter. The 

 well-developed characters of the bone indicate a bufonid 

 nature for the species as indicated above. The head, that is, the 

 ulno-radial articular surface, is as distinctly marked as in all 

 modern Salientia with which I am acquainted. The ball is 

 apparently capped with calcified cartilage. Above the ball is 

 a distinct pit for muscular attachments, precisely as in modern 

 frogs. The shaft is quite slender and nearly circular. 



The ilium (No. 1568 Yale University Museum) is quite 

 peculiar and will possibly be sufficiently characteristic to sus- 

 tain the validity of Professor Marsh's genus, Eobatrachus. 

 The element is of the right side. It measures 10 mm in greatest 

 length, by 3 mm in greatest width, by 2 m,n in greatest thickness on 

 the articular surface. The element is a slender rod, like the 



