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In studying the extinct carnivora of the Tertiary period, it has be- 

 come necessary to examine into the above definitions, in order to de- 

 termine the affinities of the numerous genera which have been discov- 

 ered. To take them up in order, I begin with the foramina at the base of 

 the skull. The result of my study of these has been, that their importance 

 was not overrated by Mr, Turner, and that the divisions of secondary 

 rank indicated by them are well founded. Secondly, as to the form and 

 structure of the auditory bulla. Although, the degree and form of infla- 

 tion are characteristic of various groups of Carnivora, they cannot be 

 used in a systematic sense, because like all characters of proportion 

 merely, there is no way of expressing them in a tangible form. For, if 

 the forms in question pass into each other, the gradations are insensible, 

 and not sensible, as is the case with an organ composed of distinct parts. 

 The same objection does not apply so much to the arrangement of the 

 septa of the bulla. The septum is absent in the Arctoidea of Flower 

 (Ursidce of Turner), small in the Cynoidea (Flower, Canidm Turner), and 

 generally large in the ^Eluroidea (Flower, Felidm Turner). But here oc- 

 curs the serious discrepancy, that in the Hysenidse, otherwise so nearly 

 allied to the Feliclse, the septum of the bulla is wanting. Nevertheless, 

 the serial arrangement of the order indicated by Flower, viz. : commenc 

 ing with the Arctoidea, following with the Cynoidea, and ending with the 

 ./Eluroidea, is generally sustained by the structure of the auditory bulla, 

 and by the characters of the feet and dentition, as well as of the cranial 

 foramina. Turner's arrangement in the order, Ursidse, Felidse and Cani- 

 dae, is not sustained by his own characters, and its only support is derived 

 f?om Flower's observations on the external or sylvian convolution of the 

 hemisphere of the brain.* There are three simple longitudinal convolu- 

 tions in the raccoons ; in the civets and cats the inferior convolution is fisr 

 sured at the extremities, while in the dogs it is entirely divided, so that 

 there are four longitudinal convolutions between the Sylvian and median 

 fissures. 



An important set of characters hitherto overlooked, confirms Flower's 

 order. I refer to those derived from the turbinal bones. In the ursine 

 and canine forms generally, the maxilloturbinal is largely developed, and 

 excludes the two ethmoturbinals from the anterior nareal opening. In the 

 Feline group, as arranged by Turner, the inferior ethmoturbinal is devel- 

 oped at the expense of the maxilloturbinal, and occupies a part of the 

 anterior nareal opening. These modifications are not, so far as my expe- 

 rience has gone, subject to the exceptions seen in the development of the 

 otic septa and molar teeth, while they coincide with their indications. 

 The seals possess the character of the inferior group, or Ursidse, in a high 

 degree. 



The characters derived from the paroccipital process are of limited ap- 

 plication, as the study of the extinct forms shows. 



* Proceedings Zoological Society, London, 1859, p. 482. 





