962 THE JOHN DAY FAUNA. 



much shorter and more slender than that of Uncia concolor, U. pardus, 

 Cyncelurus jubatus, or Crocuta maculata. What its length relatively to the 

 other digits is, cannot be readily ascertained at present. Its proximal ex- 

 tremity is formed much as in the recent Felicke and Eycenidce, except that 

 there is scarcely any external angle, from which it results that the bone is 

 narrower when seen from the front. The shaft is subcylindric, is distally 

 somewhat flattened, and is gently bowed forwards. The epicondyles and 

 extremital keel are well developed, and much as in the recent species. 



Measurements of posterior limb. 



M. 



{transverse 045 

 anteroposterior at middle I g^«"^t*«* "^"^ 

 (least 020 



Diameters of shaft at distal fourth ^ ^ '". .,„ 



( anteroposterior 01b 



Diameters of distal end of tibia? "■ „,„ 



( anteroposterior Oia 



_. , » i 1 < transverse at middle 024 



Diameters of astragalus •; „„„ 



( anteroposterior Vis 



Length of trochlea on external crest 029 



Width of head 018 



Length of first metacarpal 067 



Anteroposterior diameter metacarpal V ^ % 



< distal 013 



Width of shaft at middle 009 



Width at epicondyles 013 



Restoration. — It is probable from what has preceded, that the Archce- 

 lurus debilis was an animal presenting much the appearance of the existing 

 cats, and of about the size of the American panther. Omitting more tech- 

 nical characters, it differed from this and other species of the Felidce in the 

 greater slenderness of its feet. Its head was characterized by less breadth 

 through the posterior part of the cheeks, and by a greater convexity of the 

 forehead between the eyes, and a greater prolongation backwards of the 

 same region. 



Its structure plainly indicates that this species was of less sanguinary 

 habits than the exising Felidce, since its prehensile organs, both of the feet 

 and dentition, are less robust. The slender zygomata and rami of the lower 

 jaw show also that the impact of its bite was less powerful, although the 

 large size and narrow form of the sectorial teeth furnish an effective cutting 

 apparatus, which in some degree supplements the deficiency of strength. 

 The weakness of the rami is further provided against by the curious exos- 



