TRIMERORHACHIS, A PERMIAN AMPHIBIAN 255 



There are various species among the material known as Tri- 

 merorhachis; of that there can be no question; as also of Eryops; 

 but when one species is based upon an isolated scapula, for instance, 

 another on the comparative size or minor distinctions of a skull, 

 and a third upon a vertebra, one is tempted to ask: What is the 

 use y 



It need not be said that the differences of occipital condyle, 

 pectoral girdle, vertebrae, and limbs in T rimer orhachis are of more 

 than family importance. Doubtless some day, when we know the 

 forms better, the genus or genera will be separated into a group 

 of higher rank. 



