94 MR. G. BUSK ON THE ANCIENT OR 
publication of an excellent figure of the tooth in question by Professor Boyd Dawkins, 
in his paper on R. leptorhinus (R. hemitechus)’. 
The above citation may suffice to show that in Dr. Falconer’s opinion the Gibraltar 
tooth belonged to the same species as that figured by Prof. Boyd Dawkins, which 
is undoubtedly R. hemitachus. 
Again, with respect to the molars, Dr. Falconer observes (op. cit. p. 829) that the 
character which best distinguishes them from those of all other species lies in the 
peculiar form of the “crochet” or promontory, projected forwards from the posterior 
colline into the transverse valley. ‘‘ In all species, fossil or recent,” he says, “ except 
R. hemitechus, the ‘ crochet’ forms a plate, which is emitted at a very open angle with 
the posterior colline, and directed more or less diagonally towards the anterior outer 
corner of the crown.” Again (p. 331), “ if the penultimate true molar in R. hemitechus 
be examined, the crochet presents a thick massive body thrown straight forward, and 
forming an acute angle with the anterior margin of the posterior barrel. It is flat or 
concave above [externally] and convex below [internally], narrow at the base, and 
thickening to a blunt margin. In mass it bears a much larger proportion to the disc 
of the hind barrel than in most of the other species. In the corresponding molars of 
R. megarhinus, Christ. (pl. iii. fig. 5, of Christol’s Mem., and pl. ii. fig. 5, Gervais’s Palé- 
ontol. Frang.), besides the difference of alignment in its offset from the hind barrel 
the section of the crochet is wedge-shaped, thinning from a broad base to a sharp 
edge” *. 
But it is needless to say more with respect to the hemitcechine characters of the 
Gibraltar teeth, so far as Dr. Falconer’s opinion respecting them is concerned. Besides 
the reference he himself gives to the specimen (B. M. No. 36770) figured by Prof. 
Boyd Dawkins, the exact correspondence between the figure of m. 2 of R. hemitechus 
given in Paleontographical Memoirs, vol. ui. pl. xvi. fig. 1, with fig. 4, Pl. X. of this 
communication, cannot fail to satisfy us of the identity of the two forms, and of their 
distinction from that presented by 2. megarhinus, Christ. 
I have not thought it necessary to say any thing with respect to the points by which 
the Gibraltar teeth are distinguished from the corresponding ones in R. tichorhinus, 
the differences in all respects being too marked to require comment. Nor, having 
shown their apparent identity with those of R. hemitechus, is it requisite to say much 
respecting their distinction from the molars of 2. etruscus, which species would other- 
wise naturally have suggested itself as a very likely subject of comparison, nor 
respecting their relation to the teeth of R. bicornis, which, again, might have suggested 
itself as not unlikely to be found in company with H. crocuta. 
As regards R. etruscus, the figures and descriptions of the Gibraltar teeth already 
‘ Journal of the Geological Society, vol. xxiii. pl. x. fig. 5. 
? T am inclined, from my own observations, to think that Dr. Falconer placed, perhaps, too much importance 
upon the characters afforded by the “ crochet,” which appear to be very variable. 
