1010.] "Marsiipiar' Characters of CreodontH. 301 



No. !). The "lui-o-e size of the hinibar vertebra; as compared with the 

 dorsals, and their tendency in some forms (Opossums) to develop the double 

 tongue and groove articulations." Possibly correlated originally with 

 arboreal hal)its. Large lumbars preserved in many i)rimitive Unguiculates. 



No. 10. The "large deltoid crest and characteristically broad distal 

 end of the humerus." This character was prol)al)ly establislied in the verv 

 remote ancestors of the mammals (see p. 119). It is preserved to a oreater 

 or less extent in several orders (p. 437). 



No. 12. The "subequal size of ulna and radius" (/. c, of shaft). Un- 

 doubtedly another very ancient character, preserved in several orders. 



No. 13. The "large size of the lesser trochanter of the femur." A 

 primitive mammalian character. Very pronounced in Cynodonts (p. US), 

 INIonotremes (p. 154), Triconodonts (?)^; progressively reduced in Marsu- 

 pials, Creodonts, Fissipeds. I^ower trochanter relatively large in J'iverravus 

 protenus (Matthew, 1901, p. 11) /. c, in a representative of the Carnassi- 

 dentia. 



No. 14. The "large size of the fibula and its extensive articulation with 

 the proximal surface of the astragalus instead of upon its outside. " Another 

 primitive mammalian character, antedating the development of a vertical 

 external malleolar facet on the astragalus. 



No. 15. The "very primitive form of the astragalus." The astragali 

 of all Creodonts appear to be much more advanced than those of the primi- 

 tive Didelphiidse; and the more generalized Creodont types represented in 

 Arctocyon, Oxycena, Sino'pa, approach the most primitive Fissiped types 

 in many respects (p. 450). 



No. 16. The "small size of the brain." A primitive mammalian 

 character which is not confined to Marsupials and Creodonts but is also 

 retained in the primitive " Carnassident" Viverravus protenufi (p. 310). 



No. 17. The "dorso-lumbar vertebral formula of 19." No doubt this 

 number of dorso-lumbar vertebrae is a very primitive one (p. 275), since it 

 occurs more or less frequently among Monotremes, Marsupials, Rodents, 

 Edentates, Insectivores and Artiodactyls. But it is not especially char- 

 acteristic of Creodonts, since it is 20 (according to Matthew, 1906, p. 231) 

 in Sinopa, Oxycena, Hywnodoyi and probably in Patriofelis, i. e., exactly as 

 in the Fissipedia. The Mesonychidfe (represented by Dromocyon) are 

 therefore the only Creodonts retaining the Marsupial number (19) of dorso- 

 lumbars. 



No. 18. The "posterior spreading of the nasals so as to exclude con- 

 tact between frontals and maxillary in front." A very ancient character 



1 This character is well shown in a cast of a small femur from the Stonesfield Slate which 

 is doubtfully referred to Triconodon. 



