Cope.] 



80 



[July 16, 



cTiidcB of the same liorizoii and locality. The horizontal and geographical 

 distribution of the species of these thirteen genera is as follows : 



Arctocyon primsevus Blv 



Hyodectes gervaisi Lem 



Heteroborus duelii Lem 



Miacis parvivorus Cope 



' ' edax Leidy 



' ' vorax Leidy 



Didymictis protenus Cope 



Pterodon dasyuroides Blv 



" biincisivus Filh 



Oxysena morsitans Cope 



" lupina Cope 



" forcipata Cope 



Stypolophus viverrinus Cope 



*' secundarius Cope . . . 



" multicuspis Cope. . . . 



" strennus Cope 



" minor Filh 



caylusi Filh 



" pungens Cope 



" brevicalcaratus Cope 



" aculeatus Cope 



" hians Cope 



Proviverra tj-pica Riitim 



Amblyctonus sinosus Cope 



" sp. no. 2f 



Palseonyctis gigantea Blv 



Mesonyx obtusidens Cope 



" lanius Cope 



Patriofelis ulta Leidy 



Lower 

 Eocene. 



N. A. 



Eur. 



Upper 

 Eocene. 



N". A. Eur 



Phylogeny. It is among the genera above enumerated that we are to 

 look for the ancestors of the existing Carnivora, excepting perhaps the 

 seals, and even these were probably cotemporaries. In those genera with- 

 out developed internal tubercles of the molars, we may look for the an- 

 cestors of the Hymnodontida, a family which early attained specialization 

 at the expense of strength of structure, and did not survive the lower Mio- 

 cene period. Such genera may be found in the MesoiiycMdcE as the later, 

 and the AmhlyctonidcB as the earlier types. 



In distinguishing between the ancestors of the Felidce and Gnnidce, we 

 naturally seek to recognize in each, an anticipation of the leading characters 

 in the dentition which distinguish those families to-day. This consists, in 

 the FelidcB, in the successive abbreviation of the true molar series from 

 behind, so that ultimately two molars are lost, and the remaining or an- 

 terior one becomes transverse. On the other hand in the Ganidce, firstly. 



+ Represented by a mandible with teeth, from Meudon, associated with l.lie 

 specimens of J'aUeonyciis in the Mus. .lardin des Plantes. 



