188 BULLETIN' OF THE 



In the Natural History Reports of the United States and Mexican 

 Boundary Survey,* Professor Baird gives much valuable information, in 

 addition to that contained in his Mammals of North America, respecting 

 the bears of the Rocky Mountain and West Coast regions of the Con- 

 tinent. On the whole it tends to render the subject still more difficult 

 and complex, if we recognize more than a single species in North America, 

 as many of the different specimens described represent intermediate stages 

 between the two commonly recognized American species. A specimen 

 collected by Dr. Kennerly, at Los Nogales, Sonora, and others at the cop- 

 per mines in New Mexico, by Mr. H. J. Clark, differ so much from the 

 " grizzlies " of California, that Professor Baird described them as a distinct 

 variety of the latter, — D^sus horribilis, var. horriccus. Although the lead- 

 ing characters are the same, this " variety " differs in being smaller, with 

 relatively shorter ears and a longer tail, these parts being nearly equal, 

 instead of the ears twice the length of the tail, as in California specimens ; 

 it also differs in the texture of the fur, in the arrangement of the colors, 

 in the greater relative breadth of the skull, its narrower and slenderer muz- 

 zle and more vaulted palate, and in the shape of the teeth. While the 

 " horriccus " specimens are quite distinct from either of the so-called varieties 

 of U. americuuus, the variation from the typical U. horribilis of California is 

 towards U. americanus ; U. americanus of the Eastern States differing from 

 them chiefly in being smaller. In the smaller size, compared with U. hor- 

 ribilis, and the great breadth of the head, "horriceus" also affiliates with the 

 U. arctos. The latter is usually supposed to never attain the size exhibited 

 by many specimens of the U. ferox (Jwrribilis) ; but Prince Maximilian says 

 that this is incorrect, as he has seen Russian bears that were fully as large 

 as the latter; and Middendorff, as already stated, remarks that the bears 

 of Northeastern Asia are as large as those of the Pacific coast of America.f 



In reference to the peculiar bears of the Sonoran region, Dr. Kennerly 

 has observed as follows : " In regard to the bears that are found along the 

 northern frontier of Mexico and the southern portion of New Mexico, 

 there seems to be some confusion. In addition to the common black bear, 



* Vol. II, Mammals pp. 24 -SI. 



t The facility with which the bear!; can cross in winter from one continent to the 

 other by way of Behring's Strait, and the known fact that they do thus cross (I am 

 assured of this fact by Mr. Dall), renders the close mutual resemblance of the bears of 

 Northeastern Asia and Northwestern America a matter of no great surprise. The simi- 

 lar resemblance between the martens and the representatives of the other circumpolar 

 species from these countries, which has been already pointed out, though some of them 

 may be able to pass k><s readily than the bears from one continent to the other, would 

 seem to be fully accounted for by a similar occasional migration, if any hypothetical 

 explanation for so natural a phenomenon as the great similarity of the animals spe- 

 cifically identical in these slightly separated districts is required. 



