1889.] NATURAL SCIENCES OF PHILADELPHIA. 



J. 16 



proeta, Proailurus, etc. The head, as in Oryptoproeta is presented 

 more obliquely inwards and upwards than in the eats; it is very 

 sharply constricted off from the neck and is evenly rounded, form- 

 ing something more than a hemisphere, and shows a distinct pit for 

 the round ligament. The great trochanter is massive and much ex- 

 tended from before backwards, but rising only slightly above the 

 level of the head, and its upper edge is more regularly rounded 

 than in the cats; the digital fossa is deep but of limited extent. 

 The ridge connecting the head with the great trochanter is. as in 

 Proa 1/ urns, mure compressed than in Oryptoproeta. The second 

 trochanter is quite prominent ; a short curved rugose line runs 

 from this point towards the lower end of the great trochanter. Of 

 especial interest is the presence of a well developed third trochanter, 

 which runs some distance down the shaft and is continued as an ex- 

 ternal linea aspera. The third trochanter appears to be universally 

 present in the creodonts, it is also found in Amphicyon (Filhol, No. 

 4a, PI. xiv, fig. 4, PI. xv, fig. 5), Cynodictis (Schlosser, No. 14, 

 p. 265), Proailurus (Filhol, No. 4, PI. 5, fig. 3), and the figure given 

 by Milne-Edwards and Grandidier (No. 11, PI. 9, fig. 7) would seem 

 to indicate its presence in Cryptoprocta, though the specimens 

 which I have had the opportunity of examining did not possess it. 

 It is further faintly indicated in certain of the Proeyonidce and 

 Viverridce, but no living carnivore exhibits it in any such degree of 

 development, as is seen in Dinietis. In the latter the shaft is rather 

 long and slender and quite strongly arched forward ; the posterior 

 surface is flattened, the anterior regularly curved from side to side. 

 The lower portion of the shaft expands gradually to the condyles ; 

 the popliteal region is nearly smooth, showing no such rugosities for 

 muscular attachment as occur in the larger cats ; it is even less ru- 

 gose than in Cryptoprocta. The condyles are of nearly equal size 

 and are quite widely separated ; above and to the side of each one 

 i< a small articular facet, apparently for sesamoid ossicles. The 

 rotular trochlea is broad, shallow and symmetrical, giving to this re- 

 gion of the bone a very feline appearance. 



The femur of Nimravus is quite different from that of Dinietis; 

 the shaft is more slender and more decidedly curved ; the condyles 

 project more strongly backward, due, no doubt, to the digitigrade 

 gait of this animal, while Dinietis was plantigrade, and the condyles 



