120 Wortman — Studies of Eocene Mammalia in the 



time their relationship with the modern Pinnipedia, the deriva- 

 tion of which may perhaps be traceable to some member of the 

 Oxyaenidse. In a paper recently published, Professor H. R 

 Osborn has dissented from these views, and expressed the 

 opinion that these forms were terrestrial or arboreal in habits, 

 and subdigitigrade* in gait. 



I shall proceed, therefore, to an examination of the paper in 

 detail, and shall first consider a method there presented, by means 

 of which we are said to be able to determine with infallible cer- 



Figure 69— Angulation of facets in feet of (I) Ursus, (II) Procyon, (III) 

 Patriofelis, (IV) Felts, showing increased obliquity in relation to increased 

 angulation. A, distal facets of metacarpals ; B, distal facets of first pha- 

 lanx ; C, distal facets of second phalanx. (Diagram after Osborn.) 



tainty the gait of an animal, living or extinct, whether planti- 

 grade, subplantigrade, or digitigrade. Professor Osborn says, p. 

 270 : " The writer has pointed out that the angulation of the limbs 

 in Ungulates is expressed in the angles which the proximal 

 and distal facets make with the long axes of the shafts; con- 

 sidering the shafts as perpendicular, facets in horizontal 

 planes indicate straight limbs / facets in oblique planes indi- 

 cate angulate limbs. Exactly similar principles apply to the 

 hand and foot of Unguiculates, as shown in Fig. 3. In the 

 passage from Otaria (secondarily plantigrade), [to] Ursus 



* Oxygena and Patriofelis Re-studied as Terrestrial Creodonts, Bull. Amer. 

 Mus. Nat. Hist., Dec. 1900. 



