222 U. Ss. P. R. R, EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
size, the usual absence of most of the small premolars, and the grayish white color of the tips 
of the hairs on the body, the American grizzly forms a remarkable and extreme geographical 
variety of the Old World, Ursus arctos; very closely related to the bear of the west coast of 
Behring’s Straits, and through this and others, by insensible degrees, affiliating with the common 
well known brown bear. 
In the lack of sufficient materials for comparing the grizzly with the Old World bear, I cannot 
gainsay thece conclusions, although perhaps the description of skins and skulls of the American 
animal herein presented may throw more light on the subject. 1 
Skull.—The skull of a grizzly bear from California, of middle age, (2037,) obtained at San 
, Francisco, exhibits the teeth almost perfectly unworn, excepting the extreme points of the 
inner tubercles of the upper molars, and the outer of the lower. The sagittal crest extends 
further forward than in the smaller American bears of the same age, reaching to the coronal 
suture. 
The upper outline of the skull is nearly straight from the occiput to the middle of the pari- 
etal crest. It then curves gently upwards, attaining its greatest elevation over the beginning 
of the posterior fourth of the frontal ; from this it slopes downwards in a nearly straight or very 
gently convex line to the anterior third of the nasal, and passes off more nearly horizontally and 
straight. The curve is much less convex than in the U. americanus, and the greatest convexity 
of the are of curvature, and greatest height above its chord, is in the posterior fourth instead of 
in the centre. . The forehead is plane between the orbital processes in its central third, exterior 
and posterior to this it is very gently convex, much less so than in the U. americanus. There 
is a decided angular depression along the middle of the nasal bones, except in the posterior 
fourth, where it is much less. 
The greater elongation of the skull in the grizzly bear is shown in the proportion which the 
width between the zygomata bears to the total length of orthographic proportion, being as 507 
to 1,000, or nearly as one to two. 
The zygomatic arch of this species is very little curved in either direction, being nearly 
straight, viewed from above, and only moderately arched. The coronoid process of the lower 
jaw is moderately concave on its posterior outline and forms a well defined right-angle with the 
superior, which curves very little downwards to meet it. 
A rather older specimen from the upper Missouri, lent for examination by Dr. Stevens of St. 
Louis, exhibits much the same characters, although rather shorter absolutely, and broader in 
proportion to its length. In this and a very old specimen from Monterey, (1218,) the median 
sagittal crest has not advanced beyond the coronal suture, although the temporal ridges are 
very decided and rise above the level of the forehead. In neither of these is there any great 
difference in the upper profile of the head, except that in No. 1218 the forehead is more depressed, 
so as to cause a slight concavity from the middle of the frontal bone to the end of the nasals. 
The forehead between the post orbital processes is also concave transversely, the orbital process 
only being rounded off exteriorly. The skull has become much broader in proportion to the 
length. (616.) ; 
1 As this article is passing through the press, I have received an elaborate paper, entitled ‘* Ueber die Selbststandigkeit 
der Species des Ursus ferox, Desm., von Pring Max von Wied, mit anatomischen Bemerkungen von Dr. C. Mayer,’’ an extract 
from the Verhandlungen der Kais. Leop. Carol. Akad. der Naturforscher, vol. XXVI. The date is not given, but it is either 
1856 or 1857. The species is very elaborately discussed, both as to its external form and internal structure. The authors come 
to the conclusion, after reviewing all of Middendorff’s arguments, that the species is essentially distinct, as a species, from the 
European Ursus arctos, especially in the shorter ears and longer claws, as well as in certain osteological peculiarities. 
