douthitt: eryops; eryopsoides. 239 



amount of shifting about of the skull after death must have re- 

 sulted in their being broken off, and indeed they must have been 

 often broken off in life. The presence of fresh scars indicates the 

 same fact. Where several scars are present, the extra ones will 

 present a different appearance, owing to the healing of the broken 

 surfaces. 



Broom speaks of the surangular as an element of the lower jaw, 

 and leads us to suppose that it is present as a separate element. 

 Were this true it would be the only case known of an amphibian 

 with a separate surangular bone. A careful examination, however, 

 of several good jaws of the Chicago collection shows not the 

 slightest evidence of the separation from the articular of the part 

 of the jaw so designated. That this portion of the articular of 

 the Amphibia was once a separate element in their ancestors, and 

 corresponds to the surangular of reptiles, seems probable; but the 

 fusion in Eryops is as complete as in other Amphibia. A well- 

 preserved jaw of the Chicago collection shows the three coronoid 

 bones as described by Broom. 



A COMPARISON OF TEXAS AND NEW MEXICO MATERIAL. 



The vertebrate faunae of the Texas and New Mexico Permian 

 are widely different from each other. Aside from the genus Eryops, 

 only two genera, Edaphosaurus and Diadectes, are recognized to 

 occur in both. Dimetrodon and Clepsy drops have been reported 

 from the New Mexico Permian, years ago, but the negative evi- 

 dence of later, more careful investigations is against their pres- 

 ence. Moreover, it is not unlikely that more complete specimens 

 will show that those remains that have been referred to Diadectes 

 represent really a closely allied but distinct genus. With such 

 slight similarity between the faunae of the two regions, there is 

 especial need to make careful comparative studies of the specimens 

 from the two regions that have been referred to these genera, in 

 order to determine whether they are really generically identical. 



Material and information concerning the New Mexican repre- 

 sentatives of Eryops are scarce. Marsh (1878) first reported 

 Eryops from New Mexico, but supposed he was dealing with the 

 remains of a reptile, and described them under the name of Ophia- 

 codon grandis. He gave us no information of value as to structure. 

 Cope, in 1881, gave us the following description of Eryops reticu- 

 latus, without figures: 



"The most prominent peculiarity of this species is seen in the neural 

 spines, which are not expanded at the summit, as in E. megacephalus, but 

 have rather contracted apices, Another character is the sharply reticulate 



