22 



AMERICAN PERMIAN VERTEBRATES 



The sacral vertebra figured herewith must also be associated 

 with this genus. The stout sacral ribs are turned downward, and 

 their articulation is partly intercentral. 



So far as the structure of the skull is concerned, as also the form 

 of the limb bones, so far as they are recognized, there is nothing 



Fig. 2. — Nothodon lentus Marsh. Sacral vertebra, from in front, natural size. 



in this genus to differentiate it from Diadectes, and inasmuch as 

 the name Diadectes has priority of ten days or thereabouts over 

 Nothodon it must stand, and inasmuch as a family name cannot be 

 based upon a synonym, if the two names are s5Tionymous the 

 family designation Diadectidae must have precedence, notwith- 

 standing the priority of Nothodontidae. If, on the other hand. 



