211—34 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
A species attaining a considerable size : m. 2 slightly shorter than the length of 
the two preceding teeth : pm- 4 relatively small, with the inner tubercle placed somewhat 
anteriorly : the earlier premolars approximated, pm. 1 larger than either pm. 2 or pm. 3 ; 
palate very slightly concave. 
It may be added that the following among other species originally referred to 
the genus Ursus really belong to other genera ; viz.: 
U. braziliensis . Lund. 
U. bonariensis. Gerv. 
U. cancrivorus. Cuv. 
U. lolor. Lin. 
U. caudivolus. Cuv. = Cercoleptes. 
U. melanoleucus . Gerv. = AEluropus. 
Microdont and macrodont forms . — Following a modification of the system adopted 
by Professor Huxley in his classification of the dogs, whereby that group is divided 
into microdont and macrodont forms according to the proportionate size of the 
cheek-teeth to that of the skull, it will be found that a similar relation holds good in 
the genus Ursus. In this genus it has been found best to take the length of m. 1 as 
unity, and to s,ee how many times that length is contained in the width of the palate 
at the same tooth. This relation is given in the following table, viz . : — 
Table showing proportionate width of palatal aspect of Ursus at m. 1 , that tooth being 
taken as unity. 
> = Arctothenum. 
j = Procyon. 
Ursus horribilis 
„ americanus 
„ arctos 
,, torquatus 
,, arvernensis 
spelseus 
ornatus 
malayanus 
,, maritimus 
,, labiatus 
3-1 
3.3 
3-3-4 
3-4 
3-5 
3-6 
3-9 
4-3 
4-6 
It is believed that all the other forms given in the foregoing list of species 
would belong to the macrodont division. It is noteworthy that the two microdont 
forms are frequently referred to distinct sub-genera or genera ( Thallassarctos and 
Species I. Ursus theobaldi, n. sp., nobis. 
History. — The cranium on which this species is founded was briefly referred to 
on page 104 of the IXtli. volume of the “ Records” as belonging to a new species 
of Ursus. 
Cranium. — The above-mentioned cranium, figured of half the natural size in 
plate XXVIII., figures 1 and 2 of the present memoir, was obtained by Mr. Theobald 
in 1875 from the Siwaliks of the Kangra district. The specimen, which comprehends 
the nearly entire cranium, has been much damaged by rolling, especially on the 
upper surface ; and from this cause the crowns of the whole of the teeth have been 
