ORDER CARNIVORA. 1453 



molars, which are differentiated into a blade and a hinder tuber- 

 cular talon, closely resemble the lower carnassial of Dasyurus (fig. 

 1 145) among the Marsupials, and of Cynodictis and Viverra in the 

 Carnivora Vera, and thus indicate how the latter group has in all 

 probability been derived from a form allied to the present family ; 

 the hinder lower molars of the Carnivora Vera having become 

 tubercular and non-secant. Other members of this family found 

 in the Lower, or Puerco, Eocene of North America are Deltatherium, 

 Chriacus, and, according to Professor Cope, Miodcenus, and prob- 

 ably Triisodon and 0?iychodectes. Didelfihodus, from the higher 

 Eocene of America, may also be placed here, as well as Qiiercy- 

 theriuni, from the French Phosphorites, and perhaps Galethylax, of 

 the Paris Eocene. Conoryctes and Hemigamts are allied Puerco 

 types ; the latter being distinguished by the fusion of the roots of 

 the upper true molars, and hence regarded by Professor Cope as the 

 type of a distinct family showing signs of affinity with the Tillodontia. 



Family Arctocyonim;. — This family is typified by the genus 

 Arctocyo?i, of the Lower Eocene of France, with which may be 

 classed Hyodectes and Heteroborus, of the Lower Eocene of Rheims. 

 Dr Schlosser suggests that Miodcenus should come in this family. 



Family Mesonychid^e. — The members of this family are short- 

 jawed forms, usually having the typical number of teeth, which are 

 less different than in the other families from those of the Carnivora 

 Vera. The type genus Mesonyx, from the North American Eocene, 

 has a grooved astragalus ; and other genera which are referred to 

 this family are Dissacus, Sarcothraustes, and Patriofelis, from the 

 latter area, and not improbably Theuritherium, of the French 

 Phosphorites. Dissacus has, however, no trochlea to the astragalus, 

 and is therefore nearer to the Proviverridce. Amblyctonus, of the 

 North American Eocene, is an allied form with the astragalus not 

 grooved, on which account it has been regarded as the type of a 

 distinct family. Palceo7iictis, of the Lower Eocene of France, may 

 be allied. 



Family Uncertain. — A few genera cannot at present be defi- 

 nitely placed. These comprise Thy lacomorfi hits, from the French 

 Phosphorites, which it has been suggested may be identical with 

 Proviverra ; and Dasyurodon, or Afiterodo7i, from the Lower Mio- 

 cene (Middle Oligocene) of Flonheim, which Dr Schlosser thinks 

 may turn out to be the same as Oxhycena gallice. Dromocyon, of 

 the Bridger Eocene, is not improbably founded upon a very old in- 

 dividual of Mesonyx ; while the imperfectly known Argillotherium, 

 from the London Clay, may prove to be identical with one of the 

 American genera. Finally, it should be mentioned that Dr Schlosser 

 would place in this suborder the genus Platychozrops, which is here 

 classed with the Tillodontia. 



