100 MR. G. BUSK ON THE ANCIENT OR 
in the Grays specimen. The os lwnare from Grays, from its size, I should refer, at any 
rate provisionally, to the larger of the two species found there, viz. A. leptorhinus 
(R. megarhinus) ; but as I have not seen any specimen of the same bone belonging with- 
out doubt to R. hemitachus, I can only employ the smaller dimensions of the Gibraltar 
bone as a doubtful argument in favour of its belonging to that species. 
The other specimens appertaining to the anterior extremity are portions of five 
metacarpal bones. Unfortunately these are all fragments of the lower end of the 
bones only. ‘They include the distal articulation, and in some nearly half of the shaft 
of two right second and two left second metacarpals, together with a similar fragment 
of the third right. To judge from their dimensions, these bones would appear to have 
belonged to two individuals, one considerably larger than the other; but, except in 
size, the corresponding bones do not appear to present any appreciable differences 
whatever. The following dimensions, giving the antero-posterior and transverse dia- 
meters of the distal articular end, will suffice to show their not inconsiderable 
difference in size :— 
in. 
i NIC 2) (a aie tie TAO Hoe: taal amedte aliyalt 
Di NOD) Ae GME Oe Sia oct stra fae tn se dal 
BecViC?2 (Gina eeerine A Ree: 9k el a eeslaragdlls 
AAMC (a) Ma Witch ot ie arta kg cial alice 
Bf MUGS (Ca) opps ey a preter Wi oem aa pes oench tema aS 
In comparison with other species, it may be noted that the distal articular trochlea 
in R. bicornis (femur of same size) is 17 x 21, in R. hemitechus (Ilford) (mean) 16 x 20, 
and in R. megarhinus, Grays, 2°1%2°5. These numbers afford additional evidence of 
the close similarity between the Gibraltar species and F. hemitechus, and at the same 
time of its distinctness from R. megarhinus. 
4, Hinder Extremity. 
The only clearly recognizable specimens belonging to the femur are (1) a fragment 
consisting of about the upper third of the bone of the right side, and (2) a detached 
third trochanter, with a portion of the shaft from which it springs, and, without doubt, 
belonging to the same bone. 
(1) The larger portion (Pls. XII. & XIII.) presents the head considerably abraded on 
the upper surface, the entire trochanter major and a portion of the shaft rather more 
than six inches long below the head; and on the inner border is the prominent tro- 
chanter minor, the lower point of which is at a distance of 5’"6 below the lower border 
of the articular head. On the anterior aspect (Pl. XII.) the bone is much excavated 
below the head and trochanter, which arches over it on the upper and outer part. 
A slightly elevated ridge runs directly downwards from the outer border of the arti- 
