320 DESCRIPTION OF AN EXTINCT 



1. A fragment of the lower jaw of the Mastodon. 



2. Two isolated upper molars and an inferior last molar of a large species of Bison. 



3. An upper and a lower molar of Equus Americanus, Lcidy. The latter, with some 

 small fragments of the lower jaw, adhere to a thick layer of oxide of iron impressed with 

 the marks of three other molars. 



4. Several fragments of hones more or less enveloped in oxide of iron, and not cha- 

 racteristic. 



The collection of remains obtained by Dr. Dickeson at Natchez, preserved in the cabinet 

 of the Academy, belong to the genera Megalonyx, Mylodon, Bison, Cervus, Equus, Masto- 

 don, and Ursus. 



From the associated remains found in this locality, the extinct species of Felis, indicated 

 by the portion of lower jaw, which I propose to designate as the American Lion or Felis 

 atrox, was cotemporary with the Mastodon, Megalonyx, Mylodon, Bison, Cervus, Equus, 

 and Ursus. 



The exact outline of the jaw in the specimen is difficult to ascertain, from its thick fer- 

 ruginous coating, but from several exposed points of the body along its base it appears 

 to have been a little convex downwards, as is frequently the case in the Lion. The sym- 

 physis rises in the gradual convex manner more usual in the latter than in the Tiger. The 

 hiatus anterior to the molars is long, in correspondence with the size of the animal, but 

 as in the Lion it rises relatively higher in its advance to the canine alveolus than is com- 

 monly the case in the Tiger. 



No remains of the incisors exist in the fossil. The canine tooth is much mutilated ; the 

 summit and back part of the crown, and a layer from the fang being broken away. It 

 appears originally to have been about six inches in length at its anterior convexity, and 

 about fifteen lines in its antcro-posterior diameter, and ten in its transverse diameter, at 

 the enamel border of the crown. Its form also appears to have been closely what it is 

 in the recent Lion and Tiger. Upon the inner side of the crown a portion of the charac- 

 teristic longitudinal ridge exists, which is more prominent at its expanded base than in the 

 animals last mentioned. 



The crowns of the molars externally at their base are not so prominent as in the Lion, 

 Tiger, and Felis spekea, and appear in consequence more vertical and less convex. 



The form of the carnassial tooth is very nearly the same as in all species of Felis. The 

 obliquity of the cutting edges and the fissure separating them correspond pretty closely to 

 the Tiger. The posterior lobe is one-fifth greater in its antero-posterior diameter than 

 the anterior lobe, and it is strongly and evenly convex postero-extcrnally. The point of 

 the anterior lobe does not rise so abruptly or prominently as in the Tiger, or Felis spetea, 

 as represented in Cuvier's figure 7, plate 191, of the 4th edition of the Osscmcns Fossiles, 

 and its base externally presents a slight salient line or ridge. 



The second molar tooth is relatively much greater in its antcro-posterior diameter con- 

 trasted with its length, than in the Lion, Tiger, or Felis spelaea. The middle lobe of the 

 crown is compressed conoidal, with a salient edge, and measures 6| lines at its base 

 externally between the depressions separating it from tin- anterior and posterior tubercles. 



