CHAP. XIV.] 



THE CATS HEXICOLOGY. 



505 



claws which, unUko those of cats, dogs, and other existing carnivora, 

 were nearly flat, straight and blunt. In none did the carpus 

 contain a scapholunar bone, but it had two separate bones in its 

 place. The jaws of the Crcodonta were long and rather slender, 

 containing a number of molars, all more or less alike, and (in most 

 genera) all sectorial in form, instead of being differentiated into 

 a few simple premolars and one large sectorial tooth, with one or 

 two tubercular teeth behind it— as are the teeth of almost all 

 existing carnivora. The astragalus, moreover, instead of pre- 

 senting that peculiar pulley-like shape which we have seen in the 

 cat, presents in almost all these creatures a plain flat surface as in 

 the existing Insectivora, Rodentia, Proboscidea, and Apes. 



One of these eocene forms has been called Provkcvra, by Riitimeyer, 

 and Gaudry* has described a similar form (from the Phosphorites de 

 Quercy), which, in many respects, reminds us of Marsupials. The 

 angle of the mandible, however, is not inflected, and the bony palate 

 is well ossified, and there are only six incisors in the upper jaw. 

 The teeth behind the canines (of which there are six or seven in 

 each jaw) are all sectorial, except the last upper one, which is placed 

 transversely. The cerebrum is so little developed that not only the 

 cerebellum but even the corpora quadrigemina are uncovered by it, 

 while the olfactory lobes are largely developed. 



Pterodon f is a form very similar to the last, with several sectorial 

 teeth in each jaw. The structure of the feet of this animal is as 

 yet unknown. 



OxycenaX is an American mammal, some individuals of which 

 were as large as the jaguar. It is closely related to the European 

 form Pterodon ; but there are but two superior true molars, and the 

 last of these is driven in transversely. The first true upper molar 

 is the sectorial tooth, instead of the sectorial being the last premo- 

 lar, as in existing Carnivora. The two last inferior molars are 

 described as " tubercular-sectorial." 



^ Stijpolophus is another American mammal, said by Cope § to 

 difier from Oxycena only in certain details of tooth structure, namely, 

 in having the three last lower molars " tubercular-sectorial." 



Mesonyx\\ is very similar to the preceding, and also American. It 

 has seven inferior teeth behind the canines, but " the trochlear face 

 of the astragalus is completely grooved above as in the true Car- 

 nivora, and its distal end presents two facets, one for the cuboid and 

 the other for the navicular bones." 



* See A. Gaudry's Encliainements du 

 Monde Animal, p. 20, figs. 13-15. 

 This genus is the Cynohvffinodon of 

 Filhol. 



t Gaudry, I. c, pp. 15-24, figs. 5 

 and 6 ; see also Gervais, Paleontologie 

 Fran5aise, p. 236, plates 11 and 26, and 

 Filhol, Ann. des Sc. Geol., vol. viL, 

 p. 218, figs. 184-188. 



% See Cope's paper on Creodonta, read 



before the American Philosophical Society 

 in July, 1880, p. 2. 



§ Cope, I. c, p. 3. 



II Cope, I. c, p. 2; and see also his 

 paper on the Flat-clawed Carnivora of 

 the Eocene of Wyoming, in Pro. of the 

 Anier. PhiL Soc, vol. xiii., No. 90, 

 1873. Professor Cope believes that 

 Synoplotherium is really a species of 

 Mesonyx. 



