394 MAMMALIA. 



teeth from the Lower Pliocene (Siwalik Formation) of India have been 

 provisionally ascribed to it. The largest known species is A. giganteus, 

 about as large as the European brown bear, and widely distributed in the 

 Middle Miocene deposits. 



Hemicyon. The dentition lacks only upper m. 3. The other two 

 upper molars are almost square in shape, while the sectorial pm. 4 is low- 

 crowned and triangular in shape, the inner tubercle being relatively large 

 and median. The typical and only known species, H. sansaniensis, is 

 represented by jaws and other fragments from the Middle Miocene of 

 Sansan, Gers, France. The animal must have been about as large as a 

 wolf. 



Hyaenarctos (fig. 221). The dentition is nearly complete, but one of 

 the diminutive premolars is sometimes wanting, while upper m. 3 seems to 

 be always lost. The canines are remarkably stout and rounded, not com- 

 pressed to an edge behind. The upper sectorial pm. 4 is low-crowned, 

 triangular in shape, and almost as broad as long owing to the relatively 

 great development of the inner median tubercle. Upper m. 1, 2 are 

 nearly square in shape. The lower sectorial m. 1 and m. 2 are antero- 

 posteriorly elongated, while m. 3 is relatively small and rounded. An 

 ulna probably referable to this genus, exhibits a long olecranon process, 

 thus differing from the corresponding bone of the bears and resembling 

 that of the dogs. The typical and best-known species is Hycenarctos 

 sivalensis from the Lower Pliocene (Siwalik Formation) of India, with the 

 skull nearly half a metre in length. Large teeth have also been obtained 

 from the supposed Pliocene of China, the Lower Pliocene of Pikermi, 

 Greece, and the Red Crag of Suffolk. Smaller species are also represented 

 by fragments in the Middle and Upper Miocene of France, Spain, Germany, 

 Austria, and northern Italy. 



The true bears, or Ursidae, are unknown below the Lower 

 Pliocene (Siwalik Formation) of India, and do not appear in 

 Europe until the Upper Pliocene, while there is no record of 

 them in North America before the Pleistocene. Their molar 

 teeth are always relatively large, while pm. 1 to 3 are diminu- 

 tive, one or more being often absent in the adult. The genus 

 Ursus itself has the sectorial tooth above and below antero- 

 posteriorly elongated, each with only two roots ; while the 

 molars (two above and three below) are also longer than broad. 

 Characteristic portions of this dentition have been obtained 

 from the Lower Pliocene of the Siwalik Hills ( U. iheobaldi} and 

 from the Pleistocene of the Narbada Valley ( U. namadicus) in 

 India ; and there is also similar evidence of small species in the 

 Upper Pliocene of France ( U. arvernensis, fig. 222) and Tuscany 



