1870.] BUSK RHINOCEROS OF ORESTON. 463
As regards dimensions, so far as they can be employed in the
distinction of the quaternary species of Rhinoceros, little need
be said. It may be broadly stated, at any rate, as regards R.
tichorhinus, R. leptorhinus, and R. hemitoechus, that although the
leptorhine teeth on the whole are the largest, the differences in
this respect are so trifling, and the variations so considerable, that
but little reliance can be placed upon deductions drawn from a single
tooth ; I shall therefore content myself in the present instance
with simply giving the dimensions of the Oreston m 1 or m 2.
in. Length 2-3 Width at anterior column 2-5 Width at posterior column 2-0
These dimensions, or at any rate the two former, are exactly the same as in three instances recorded by Dr. Falconer, from Lyons, Nice, and Imola — although it is true they are less than in the general run of British specimens in the British Museum, in which the mean of the corresponding dimensions maybe taken as 2-6 x 2-5.* But in partial explanation of this, it must be considered that, at the height to which the crown has been reduced in the Oreston specimens, they scarcely afford the full dimensions of the entire tooth.
Lower Teeth. — The two lower molars, to which alone I need refer, are nos. 880 and 881. The former (Fig. 3) is the crown por-
Fig. 3. — Crown of second Lower Molar of Rhinoceros from Oreston.
Fig. 4. — Fourth Lower Premolar of Rhinoceros from Oreston.
tion of m 2 ; and, with respect to it, all I would remark is, that the deep excavation of the worn surface, in consequence of which the
which I have adverted, and which he also assigns to R. leptorhinus, and further states that he is unacquainted with any other instance of what he terms "a bridge-crochet" in a true molar having been figured, "although," he says, " in the milk-molars it is by no means of rare occurrence." He also remarks that this appearance "must not be confounded with the cohesion between the ' crochet' and the 'combing' plate which gives rise to the third fossette, so characteristic of R. tichorhinus " (p. 33).
- It is, perhaps, not improbable that the Oreston teeth may be milk-molars.
