CREODONTA 607 
sections into which the order has now become broken up. By some 
zoologists these have been supposed to be Marsupials, or at least to 
show transitional characters between the Metatherian and Eutherian 
subclasses. By others they are looked upon as belonging altogether 
to the latter group, and as the common ancestors of existing 
Carnivores and Insectivores, or perhaps rather as descendants or 
relatives of such common ancestors, retaining more of the generalised 
characters than any of the existing species. They shade off almost 
insensibly into numerous other forms less distinctly carnivorous, 
to the whole of which, including the modern Insectivora, Cope 
(to whom we are indebted for much of our knowledge of the 
American extinct species) gives the name of BUNOTHERIA, those more 
specially related to the existing Carnivora forming the suborder 
Fic. 278.—Anterior portion of the skull of Hyenodon leptorhynchus. (After Filhol.) 
Creodonta. These are instances, however, in which the application 
of the principles of classification adopted in the case of existing 
species, of which the entire structure is known, and which have 
become divided into isolated groups by the extinction of inter- 
mediate forms, is almost impossible. If the generally accepted view 
of evolution is true, and the extreme modifications pass insensibly 
into each other by minute gradations (a view the paleontological 
proof of which becomes strengthened by every fresh discovery), 
there must be many of these extinct forms which cannot be 
assigned to definitely characterised groups. There are, however, 
some which stand out prominently from the others as formed on 
distinct types, having no exact representatives at present living on 
the earth. 
The more typical Creodonts appear, however, to be so closely 
related to the true Carnivora through the extinet Ifiacidw (p. 539), 
