Preliminary Synopsis of American Bears. 69 



KEY TO THE BIG BEARS OF AMERICA. 



Molars small and weak ; pin * with inner cusp obso 

 lete or small ; m 2 without decided heel genus THALARCTOS. 



Color, white Thalarctos maritirnus. 



Molars large and powerful ; pm 4 with inner cusp 



strongly developed ; m 2 with enormous heel genus URSUS. 



Size huge. 



Size largest (skull reaching 440 mm. in greatest 

 length ) ; frontal region enormously elevated 



above and behind orbits Ursus middendorjfi. 



Size somewhat smaller (skull less than 425 in great 

 est length) ; frontal region nearly flat. 

 pm 4 very large and quadrituberculate ; pm 4 

 large and high without heel ; m l without 



clear interspace on inner side Ursus dalli. 



pm * normal ; pm 4 moderate, normally with 

 cusp on cingulum in front of main cusp ; 

 m ! with clear interspace on inner side Ursus sitkensis. 



Size medium or relatively small. 



Temporal impressions turning in abruptly from 

 postorbital processes, nearly at right angle to 



cranial axis ; skull short Ursus richardsoni. 



Temporal impressions not turning in abruptly 

 from postorbital processes; skull longer. 

 Frontal elevated and usually convex between 



postorbital processes Ursus horribilis. 



Frontal flattened and concave between post- 

 orbital processes Ursus horriseus. 



Ursus middendorffi sp. nov. Kadiak Bear. 

 PI. IV, figs. 2, 3 ; pi. V, fig. 2 ; pi. VI, fig. 2. 



Type from Kadiak Island, Alaska, No. 54793, <? ad., U. S. Nat. Mus., 

 Dept. Agric. coll. Collected July 3, 1893, by B. J. Bretherton. (Original 

 No. 176.) 



Characters. Size huge; largest of living bears, though only slightly 

 larger than Ursus beringiana Middendorff, from Kamschatka ; frontal re 

 gion in male enormously elevated, highly arched, and relatively narrow; 

 zygomata bowed outward to an extraordinary degree ; postzygomatic 

 part of skull very short. 



The bear of Kadiak Island needs comparison with only a single spe 

 cies Ursus beringiana, of Kamschatka. It requires no comparison 

 with the American Grizzlies (Ursus horribilis Ord) or with the Barren 

 Ground bear ( Ursus richardsoni Mayne Reid). Contrasted with the Kam 

 schatka bear the forehead of the male is very much higher, more swollen 

 above and behind the postorbital processes, narrower, and more rounded ; 



