1892.] NATURAL SCIENCES OF PHILADELPHIA. 291 



A REVISION OF THE NORTH AMERICAN CREODONTA WITH NOTES 



ON SOME GENERA WHICH HAVE BEEN REFERRED TO 



THAT GROUP. 



BY W. B. SCOTT. 



The Creodonta form an extremely heterogeneou.s group, very 

 difficult to define and still more difficult to classify and subdivide. 

 This difficulty arises partly from the imperfection of the available 

 material, but more especially from the lack of diagnostic characters 

 which are common to all the members of the order and from the 

 minute steps of gradation by which they shade into other groups of 

 allied unguiculates and even ungulates. Creodonta were among the 

 earliest fossil mammals which were accurately studied and they were 

 then referred to the carnivores. Laurillard, Pomel and others, 

 however, regarded them as marsupials, and Aymard and Gaudry 

 following this example, have called them Sous-didelphes. In 1875 

 Cope proposed the name of Creodonta for the group which he 

 regarded as a suborder of the Insectivora, but in 1877 he named 

 this comprehensive order the Bunotheria, referring to it as suborders, 

 the Creodonta, Mesodonta, Insectivora, Tilludonta and Tteniodonta. 

 The creodont division has not found universal acceptance, Filhol 

 regarding them asCarnivora, Wortman as Insectivora and Lydekker 

 as a suborder of the Carnivora, Nevertheless, they cannot be in- 

 cluded among either the insectivores or the carnivores without unit- 

 ing these groups, and it is therefore most convenient to regard them 

 as an order. 



The number of genera which should be referred to the Creodonta, 

 the families into which they should be grouped, and their mutual 

 relationships are matters of great obscurity and difficulty, and opinion 

 on the subject has been both conflicting and fluctuating. The reason 

 for this lies largely in the imperfect condition of the available 

 material, the few genera, whose structure is at all completely under- 

 stood, being for the most part members of highly diflferentiated side- 

 lines, which have but little importance in estimating the character 

 of the group as a whole. More especially is this true of the Puerco 

 genera, which are known almost exclusively from teeth, together 

 with a few scattered bones, and as the trigonodont (tritubercular) 

 plan of molar tooth is so universal in that formation, the discrimina- 



