DIPLOCAULUS MAGNICORNIS 35 



crushing shell fish, as Case suggests, and Diplocaulus may have 

 fed on some of the smaller Mollusca of the Permian rivers and 

 lakes. On the lateral face of the mandible, there is a distinct 

 groove, the operculo-mandibular canal of the lateral line system. 

 It would be interesting matter to determine if this canal extended 

 entirely around the mandible. 



Dr. Case in 1908 published a restoration of the entire animal, as 

 the structure seemed to him to demand. However, Case neg- 

 lected the insertion of the clavicular girdle which was already 

 known and which would seem to indicate the presence of limbs. 

 As a matter of fact limbs are still unknown in this species although 

 Williston has recorded the discovery of small limbs in the closely 

 related species D. limbatus Cope. That limbs will ultimately 

 be discovered in the present species can not be doubted. The 

 habits of the animal were undoubtedly as Dr. Case has suggested 

 for them (Pop. Sci. Monthly, December, '08). 



Paleontology teaches us nothing as yet of the ancestry of this 

 peculiar genus of amphibians nor have we any record of its de- 

 scendants. It is one of those peculiar forms which stands alone. 

 It shows, however, characters which are more nearly those of 

 the Branchiosauria than of the Microsauria in which order it is 

 usually placed. The characters separating the early orders of 

 Amphibia are essentially those of the ribs and vertebrae. The 

 structure of the skull is essentially similar in all of the groups. 

 We are not able, from the structure and composition of the skull, 

 to distinguish a branchiosaurian from a microsaurian. The 

 characters of the ribs and vertebrae are, however, perfectly 

 constant and distinctive. Of course there are certain superficial 

 characters of the skull which hold true for all branchiosaurs and 

 microsaurs such as the absence or presence of sculpture of the 

 cranial elements and the absence of the lateral line grooves from 

 the skulls of the Branchiosauria. Other characters such as 

 the presence of external branchiae in the Branchiosauria, the lack 

 of endochondral ossification in the long bones and absence of 

 clawed digits would seem to be of considerable importance. 



Except for superficial characters the skull of Diplocaulus mag- 

 nicornis Cope is essentially similar to those of the Branchiosauria 



