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also the extent of the sagittal crest, the peculiar conformation 
of the sagittal expanse, the difference in formation of the 
forehead, the greater strength and width of the zygomata ; 
and viewed from beneath there is a striking difference in the 
shape and size of the palatal margin of the nasal cavity, as 
also in the length from the margin of that orifice to the 
pterygoid process and to the occipital condyle, the former of 
which characters Professor Eolleston, of Oxford, informs me 
are not subject to variation. 
Width of palatal margin in No. 1 . .. l£in., do. in No. 2. .. l£in. 
Length of do. to pterygoid process . . 2 do. do. . . lj 
Length from palatal margin to occipi- 
tal condyle 6£ do. do. . . 5| 
Palatal orifice to nasal cavity . . . . conical, do. do. cylindrical. 
There are other less important characters (easier to recognize 
by reference to the figures of each, copied from accurate 
photographs, obligingly taken expressly for me by Mr. 
Hanson, of Leeds, than by a verbal description). The most 
essential peculiarities, however, will be apparent by a com- 
parative measurement and enumeration of them in the two 
skulls, to which I shall refer as !Nos. 1 and 2. (See next 
page, and plate X., figs. 1 and 2.) 
From the characters just enumerated, I propose to assign 
the skulls to two different species of bears, in which opinion, 
I am happy to say, Professor Owen concurs, who says, in a 
letter to me (after seeing photographs of the skulls), " I do 
not regard No. I. as specifically the same with your No. JX" 
The larger, which somewhat resembles in form the Ursus 
maritimus, but has belonged to an animal vastly superior in 
magnitude, and very nearly equal to spelgeus, I propose to 
call Ursus planafrons, from the peculiar flat receding form of 
the anterior portion of the head. But it differs from the 
Polar Bear in the form of the orbital expanse, which in the 
latter is obliquely triangular, while in the former it is more 
