546 
EEPOBT ON THE EXPLOEATION OE BEIXHAM CAVE. 
exhibit less trenchant distinctive characters. The last premolar, though usually very 
much the larger in TJ. spelceus , presents no difference in form. In both it is tricuspid, 
and the relative sizes of the cusps appear to be much alike in both. In TJrsus arctos I 
have noticed two distinct forms : one exactly resembles that in TJ. spelceus, TJ. priscus, 
and TJ.ferox , and is tricuspid, whilst occasionally the small inner cusp is entirely wanting, 
and the smaller hinder outer one is so much diminished in size as almost to give the 
tooth very much the form that it has in TJ. maritimus, in which the hinder cusp is very 
much less in proportion to the anterior. I am unable to point out any peculiarities 
between the different species beyond size in the penultimate upper molar; and with 
regard to the great tubercular molar, it presents such extraordinary diversities in size 
and form in one and the same species, that I have been at loss to seize any satisfactory 
characters in it. Speaking generally, as regards form, the last molar in TJ. spelceus is 
less contracted behind than it is in TJ. ferox (under which I include TJ. prisms ) and TJ. 
arctos ; but so many exceptions occur to this that the character becomes of little real 
value. Nor in minor particulars am I better able to discern any upon which it is worth 
while to dwell. But there is a sort of coarseness, as it may be termed, in the sculpturing 
of the tooth which appears to distinguish it from that of either TJ. speloeus or TJ. 
arctos. Most of the Brixham teeth have altogether the facies of TJ. prisons , and there 
is certainly none which can be referred to TJ. spelccus. But among the teeth is one so 
remarkable for its size amongst the others and for its form as to demand passing notice, 
although it probably has no more than an individual peculiarity. This tooth is shown 
in fig. 14, Plate XLYI. It is a left upper last premolar, fully as large as the mean size of 
that tooth in TJ. spelccus ; and the inner cusp, instead of being single, is subdivided into 
three distinct points, of which the middle one is nearly as large as the usually single 
cusp occupying that situation. 
From the foregoing particulars, it would seem that the majority of the Brixham 
teeth exhibit, not only in their size but also in their form, the characters rather of 
TJ. prisons than of TJ. spelceus, of which latter species indeed we have, so far as I can 
perceive, extremely scanty evidence among the cave remains. 
Although it is quite certain that the true TJ. spelceus has been by no means rarely 
met with in Britain, not only in caverns, but also, as it would seem from the Bacton 
specimen, in lacustrine beds, associated in both cases with the older extinct mammals, 
it appears to me, from what I have been able to observe in ursine remains from Ireland, 
that they are all referrible to what I should term TJ. ferox fossilis. No undoubted 
instance of the former existence of TJ. spelceus in Ireland has as yet occurred to me ; 
and although it elsewhere most certainly coexisted with TJ. prisons , it appears, so far as 
I have been able to go into the subject, to be tolerably clear that the latter species, 
more especially towards the later period, has in this country been the more abundant of 
the two as a fossil, and has even survived to the present day in western North America 
under the form of TJ. ferox. 
