64 ON THE EXTINCT MAMMALIA OF 



second premolar and the fangs of the teeth in front and behind. The space occupied 

 by the three molars was about two inches, or half an inch more than in D. x^rimcmus. 



The crown of the second premolar, preserved in the fragment, is seven lines wide 

 and has been at least half an inch in length. The summit of its principal cusp is 

 much worn off, and a groove is worn at the base externally of the posterior talon. 



The jaw fragment below the second premolar is fourteen lines in depth. 



A fragment of the right side of the upper jaw, containing the fang of the canine 

 tooth, probably belonging to the same species, if not the same individual, as the 

 former specimens, exhibits the fang throughout its length. This is about Ih. inches, 

 while the breadth at middle is 13 lines and the thickness 6 lines. 



DINICTIS. 



DiNICTIS FELINA. 



The above generic name has been given to a remarkable carnivorous animal which 

 exhibits a relationship with the Weasels, Pidorins, and the Sabre-toothed Tiger, 

 Drepanodon. It has the same formula of dentition as the former, but in the general 

 form and constitution of the skull and teeth it is more like the latter. A single 

 species has been discovered, and was first indicated under the name of Dinictis felina, 

 from the specimen of an almost complete but much mutilated skull, obtained in the 

 Mauvaises Terres of White River, Dakota, by Messrs, Hayden and Meek, for Prof. 

 Hall, by whom it was submitted to my examination. Subsequently Dr. Hayden 

 discovered a second skull, the one represented in figure 1, of plate IV, which was 

 purchased for the museum of this Academy. 



The skull of Dinictis felina presents a near resemblance in size, proportions and 

 constitution to that of its predatory accomplice, the Drepanodon primoiv'us. 



The upper part of the face, in relation with the cranium back of the bifurcation of 

 the temporal ridges, forms a more inclined slope than in D. jJrimcevus. The cranium 

 is proportionately rather larger and the face somewhat shorter. The forehead is 

 rather narrower, more convex transversely and less depressed along the middle. The 

 muzzle is shorter, while it retains about the same breadth. The orbits are larger, as 

 in the true cats, but they are more open posteriorly than in either the latter or 

 Drepanodon primoivus. The post-orbital processes of the frontals appear to have been 

 comparatively short J those of the malars were about as short as in the last named 

 animal. 



The temporal fossa has nearly the same form, proportions and relative capacity as 

 in D. primoevus. The posterior root of the zygoma does not originate so low, and 

 occupies a relative position more like that of Felis than of D. primcevus. 



1 



