207—30 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
bear is undoubtedly ur sinus, which was applied by Shaw in 1791, and if the generic 
term Melursus is employed, there can be no objection to using this specific name. If, 
however, the animal is referred to the genus TJrsus the old specific name becomes 
practically fidiculous, and it then appears preferable to adopt Blainville’s later specific 
name of labiatus. 
With the exception of the last-named species in which, as already observed, the 
upper incisors are only two in number on each side, the typical adult dental formula 
of all the members of the genus TJrsus is I. f, C. j, Pm. M. The whole of 
the premolars are relatively small ; and this is especially the case with the first three, 
some or all of which very frequently fall out as age advances. The carnassial teeth 
have not the markedly sectorial character of the majority of the Carnivora ; and the 
hinder molars have flat tuberculated crowns. There is a considerable amount of 
variation in the relative development of the cusps on the crowns of the cheek-teeth ; 
these being most developed in the grizzly ( U. horribilis ) and polar bears ( U. 
maritimus ) ; and perhaps least so in the aswail ( TJ. labiatus). This shows that 
no indication as to the carnivorous or frugivorous habits of the bears can be 
drawn from the characters of their molars, since while the polar bear is entirely 
carnivorous, the grizzly mainly subsists on a vegetable diet. 
As the specimens to be described below only comprise a skull and part of the 
upper jaw it will suffice to notice on this occasion some of the more important 
distinctive characters of the upper molars, the specific characters of which will be 
noted in later paragraphs under the head of the respective species. For fuller 
details the reader is referred to Professor Busk’s memoir on the “ Quaternary Fauna 
of Gibraltar.” 1 
The upper carnassial is a triangular tooth, which, however, may still be divided 
into a ‘ blade ’ and ‘ tubercle’: the relative position of the latter affording an 
important point of specific distinction : a minute cusp is sometimes found at the 
anterior edge of the main cusp of the tubercle, thus showing that the latter corresponds 
to the posterior inner cusp of the typical tooth. The first upper true molar is an 
oblong tooth, of a transitional character between the carnassial and the second true 
molar ; the outer side of the crown carries two large cusps, corresponding to the 
‘ blade ’ of the carnassial, and varying in their degree of development in the 
different species, and the inner side has a ridge, divided into two or three more or 
less distinctly defined cusps, the first and last corresponding to the inner cusps of 
the typical mammalian tooth : these may be termed the main cusps, and the middle 
one the accessory cusp. The second true molar is produced posteriorly into a talon, 
where it is generally more or less cut away on the outer side. The essential 
characters of the fore part of this tooth are very similar to those of the first true 
molar, but its cusps are less distinctly defined. 
Distribution . — At the present day true bears are found over the greater part of 
i ‘ Trans. Zool. Soc. Lon.’ vol. X. 
