DAKOTA AND NEBRASKA. 31 



Space occupied by the back five molars, . 



Space occupied by the tubercular molars, 



Depth of jaw below middle of sectorial molar, 



Thickness " " " " 



Thickness of jaw below third premolar, . . 10 " 6 " 5| " 



Thickness of ascending border of ramus an inch 



above the alveolar border of tlie sectorial 



molar, . . . . . 8 " 4i " 4 " 



Thickness of do. an inch and a half above the same, 8 " 3 " 2i " 



Antero-posterior diameter of third premolar, . 7 " 7 " 6* " 



" fourth " . 10 « 8 " 7i " 



Thickness of do., . . . . 5 " 3^ " 3i " 



Antero-posterior diameter of sectorial molar, .17' "f 14 J " 14 " 



Thickness of do., . . . . 7i " 5i " 5i " 



Antero-posterior diameter of first tubercular molar, 8J " t 6 " 6 " 



" " " second " " 5 " J 3 " 3 " 



AMPHICYON. 



An extinct genus of carnivorous animals, named Amphicyon by M. Lartet,§ from 

 some fossil remains found in the miocene formation of Sansans, France, would appear, 

 by the general form and contraction of the teeth, to belong to the family of the 

 Wolves, Caniclce. From slight differences, however, in the dentition, together with 

 characters drawn from the skeleton, M. De Blainville|| viewed the genus as rather 

 belonging to the family of " Petits-ours," or little Bears, or of " Subursus," as he 

 calls it. 



MM. De BlainviileT[ and Gervais** ascribe to the molar series oi Amphicyon ?k 

 formula differing from that of other genera of Canidm, in the possession of an 

 additional or third tubercular molar to each side of both jaws. M. Lartet,tt who first 

 indicated the genus, mentions as the chief character distinguishing it, the presence of 

 a third tubercular molar to the upper molar series, but makes no mention of the 

 number of teeth in the lower jaw. In M. De Blainville's figures of the specimens, 

 in plate, Subursus, xiv, of the Osteographie, upon which M. Lartet proposed the 



* This space would be even greater if the tubercular molars were on the same level as in the two recent 

 Wolves. 



t Allowance made for the imperfection of the fore part of the tooth. 



% Estimated, from the extent of the alveoli. 



i Bull. Soc. Geol. 1836, vii, 219. || Osteographie, Petits-ours, p. 96. I Ibid., 81, 82. ** Zool. et Paleon. 

 Franc, t. 1, p. 111. ft Supra. 



