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Show 335 Measurements qf seventeen $ kulU of URSUS ARCTOS { chiefly suhsp. HORRIBILIS). II 5* 1318 7401 3630 6905 3538 3537 3536 8086 990 3818 13345 14785 7146 6551 6548 4441 Locality. Sacramento, Cal do do Fort Tejon, 0* 1 . . . . . . do CoppoxminMtN. Mex * T . T . , * . * . . .. Medicine Bow Mountains ( eastern slope).. Big Porcupine Creek, Mont j Franklin Bay, Arctio Sea | . . . . . . d o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . do Russia.. Sex. 9 1 0* 9 < f I 15.60 15.75 14.05 16.00 15.40 1X85 14.75 14.50 14.40 14.50 14.75 13.85 13.45 18.35 1& 40 18.45 1X75 Width. 9.05 7.75 a 50 a io 7.45 aw 9.80 a oo a as aso 7.40 a 90 7.30 a 65 7.85 7.53 Bertarka. Very old. Do. Very old. Do. Var." horriccu* " Baird. Do. " Barren Gronnd Bear." Do. Do. The question of the relationship of the large Bears of Forth America to those of the Old World has long been a vexed one, and is, of coarse, one not easily settled. In the present collection are thirty- three skulls, representing various ages, but the greater part are adult. These include two only from the Old World, six from the Arctic coast, eleven from California, and fourteen from various localities in the Rocky Mount* ains, from Idaho Territory to Arizona. Among the American specimens are two rather easily distinguishable forms, one of which is the large Grizzly, or U. horribilis of authors, from the western parts of the United States; the other, the smaller so- called Barren Ground Bear of Arctic America j both being undoubtedly specifically distinct from ^ he Ursus amerteanus. The Barren Ground form* differs from the more southern Grizzly not only in its smaller size, but in its strong tendency to a depression of the frontal region of the skull, where the simple flattening of this region in the Grizzly is here often carried so far as to form a well- marked concavity as in the true arctos of the Old World. Sometimes, however, U. horribilis also presents a considerable depression between the postorbital processes, as great even as in average specimens of 17. arctos, as is the case in No. 7401 from Monterey, Gal. The Barren Ground Bear's skull generally presents a more dog- like aspect, in consequence of the thickening superiorly of the postorbital border of the frontals, than is seen in U. horribilis, it approaching in this respect to the form seen in Ursus spelceus, where this feature attains its highest development, resulting in the very strong frontal depression so characteristic of the skulls of that species. The dentition of U. arctos, U. richardsonij and U. horribilis presents no important differences, the chief difference being the relatively rather smaller size of the teeth in the latter. The form of the last upper molar is almost precisely the same in the two first named, and the differences presented by Z7. horribilis are both slight and inconstant. In U. rich-ardsoni, this tooth narrows gradually, and about equally, on each side posteriorly, almost exactly as in U. arctos, it being widest at or near its extreme anterior border. While this is sometimes the case in U. horribilis, its greatest breadth is generally one- fifth the length of the tooth behind the anterior border, and the tooth is relatively broader posteriorly * Named by Captain Mayne Reid, in one of his stories, " Ursus Richardsoni" ! t The Barren Ground Bear skulls in the collection are labeled with this name. |
