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 &. 
tichorhinus, KR. leptorhinus, and Kk. hemitechus, 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. 
Tyskovesi 0) 2 3) Brey eames a al nat sth ead eli eta eh 2°3 
Wadthyatpanteriors column aentisciccys aie oles edeesie os 2°5 
Widthyat posterior columms (0). a eee ne tn. 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 may be 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 speci- 
mens, 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 Fig. 4.—Fourth Lower Pre- 
Molar of KRhinoceros from molar of Rhinoceros from 
Oreston. Oreston. 
tion of m2; and, with respect to it, all 1 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 Ff. deptorhinus, and further 
states that he is wnacquainted 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 cha- 
racteristic of R. tichorhinus” (p. 33). 
* Tt is, perhaps, not improbable that the Oreston teeth may be milk-molars. 
