Wortman — Studies of Eocene Mammalia, etc. 281 



Art. XXX. — Studies of Eocene Mammalia in the Marsh 

 Collection, Peahody Museum / by J. L. Wortman. With 

 Plates I-IV. 



[Continued from page 206.] 



Suborder Creodonta Cope. 



In the first part of this paper, I have given the more impor- 

 tant characters by means of which this group of the Carnivora 

 is distinguished from the Carnassidentia. It now seems desir- 

 able to enter somewhat more fully into a discussion of these 

 particulars, and I shall therefore consider some of the charac- 

 ters of less importance, from the point of view of classification. 

 The first of these which it is necessary to emphasize as a broadly 

 distinguishing feature is that the Carnassidents have been suc- 

 cessful, and have left numerous modified descendants which 

 constitute a large and important part of the living mammalian 

 fauna in almost all regions of the globe ; whereas the Creo- 

 donts failed, and have completely died out, without possibly 

 the aquatic Pinnipedia represent them in the living Carnivore 

 fauna. 



In the organization of the skull, there are a number of 

 characters that are more or less distinctive, among which may 

 be mentioned the large lachiwmal spreading out upon the face, 

 as is invariably the case among the carnivorous Marsupials 

 and a number of the Insectivora. This is true of Mesonyx, 

 Dromocyon, Harjpagolestes, Sinopa, Proviverra, Limnocyon, 

 Thereutherium (?), and very probably also of Oxyceua and 

 Patriofelis. In some species, notably the Mesonychidse, the 

 nasals are broad posteriorly, as in the Marsupials, and almost 

 exclude the frontals from contact with the maxillaries. The 

 posterior border of the palate is terminated by a thickened 

 ridge, recalling to a certain extent the structure of the marsu- 

 pial palate. In the posterior part of the palate, moreover, 

 there are very generally a large number of foramina of variable 

 size, but usually minute, situated behind the posterior palatine 

 canals, which undoubtedly represent the remains of the vacu- 

 ities so common to the marsupial skull. In certain forms, 

 especially Sinopa, and in some species of Hycenodon, as Scott 

 has shown,* there is an additional foramen in the base of the 

 skull, just in advance of the condyloid, which is also a con- 

 spicuous feature of the marsupial skull. The zygomatic arch, 

 with its component bones, is heavy, and the malar usually 

 extends well back toward the glenoid cavity. In the superior 

 molars, if either border is elongated it is always the posterior, 



* Jour. Acad. Nat. Sci., 1888, p. 178. 



Am. Jour. Sci. —Fourth Series, Vol. XI, No. 70.— October, 1901. 

 20 



