11)10.] Close Rclalionship of Crcudoiila (ind Fissipedia. 311 



foramina and architecture of the skull in the two groups. The entocarotid 

 artery in Sinopa agili.s, a primitive member of the Hysenodontida^ must 

 have entered the brain case through the foramen lacerum inedius (Wortman, 

 1901, p. 440) as in the Fissipedia. In his description of Sinopa grangeri, 

 Matthew (1900, pp. 208, 213) has noted several features which suggest the 

 Oligocene Canids Cynodictis and Dapliccnus: especially in the tympanic 

 region (/. c, p. 214), in the post glenoid region (p. 215), in the long basicranial 

 region and in the occiput. Apart from the aberrant Hyienodont features, 

 the differences which separate the skull of Sinopa from that of Fissipedia are 

 primitive features, such as the slight posterior spreading of the nasals, the 

 interorbital constriction, small brain case, small backwardly directed paroc- 

 cipital processes (an Insectivore character), and an accessory condylar fora- 

 men (see p, 218), the remains of which seem to persist in Daphcpmi.s (/. c, p. 

 214). 



The derivation of the Miacidcie and, through them, of the Fissipedia 

 from unknown Insectivore-Creodont ancestors is also indicated in the fol- 

 lowing characters of the Lower Eocene Viverravus' protenus (figured by 

 Matthew, 1901, p. 9): persistence of the astragalar foramen, heavy muzzle, 

 marked interorbital constriction, weak zygomata, long low sagittal crest 

 [cf. Pantolestes). The skull also is very large in proportion to the skeleton; 

 the tail large (presumably long) ; neck longer than in most modern Carniv- 

 ora; limbs rather short with large joints and heavy muscular attachments; 

 feet small, spreading; scaphoid and lunar separate; fibula large; humerus 

 with prominent long deltoid crest, broad distal extremity and ente})icondylar 

 foramen (Matthew). 



Conclusion. The derivation of the Fissipedia from the C'reodonta by 

 way of the Miacidse has been well established by Wortman and Matthew 

 and new evidence has been adduced by the latter author for the relationship 

 of the Miacidse and Arctocyonidse. The phalanges in the Arctocyonid- 

 Miacid-Fissipede group are always })rimitively compressed while in the 

 Mesonychid-Oxysenid-Hyjenodont group, so far as known, they are always 

 depressed and distally fissured (Matthew). It remains to show that in 

 spite of this difference both grou])s may have been derived from the Oxy- 

 clsenidte. 



(1) The two types of ungual phalanges may sometimes occur in the 

 same suborder, for Erinaceus has compressed, TaJpa has deeply fissured 

 ungues. 



(2) The two groups are not very widely separated in the Basal Eocene 

 so far as the skull and dental structures are known. For example, the skull 

 of Triisodon heilprinianus (Matthew, 1901, pp. 30-31, figs. 10-12), an early 

 Mesonychid, retains many primitive characters in common with Arctocyon; 

 nor has it assumed anv verv marked Mesonvchid features in the dentition. 



