124 MR. G. BUSK ON THE ANCIENT OR 
The mere differences in size of the other bones, as exemplified in the metacarpals 
and metatarsals, shown in Plate XXVI., is also sufficiently explained by individual 
variation. The general form of the articular surfaces will be seen to correspond; and 
although the perimetral index shows considerable differences, this is not more than 
can probably be accounted for by age and sex. - 
On the whole, therefore, there appears to be no reason to consider that more than 
one species of Ibex is represented in the Gibraltar remains. 
1. Skull—Several more or less perfect skulls have afforded material for comparison 
of this important part of the skeleton. 
The one figured in Plate XXII. fig. 1, exhibits the entire upper surface of the cranium, 
including the bases of the horn-cores in front and the entire occipital condyles behind. 
Unfortunately, neither in this nor in any of the other specimens are there any remains 
of the facial bones, except of the upper and lower jaws. 
A second skull, in a very fragile condition, but still very perfect when repaired, is 
equally if not more complete, inasmuch as it preserves a considerable portion of the 
base. It shows half of the right horn-core divided vertically and transversely, and the 
right auditory foramen, a small part of the right orbit, with the whole of the temporo- 
parietal region on the same side. From the state of the sutures the skulls must have 
belonged to mature animals, which, from the inconsiderable size of the bases of the 
horn-cores, were most probably females. 
A third specimen shows the left frontal with a part of the orbit, and an entire horn- 
core (fig. 7) of inconsiderable size, and therefore also probably female. 
A fourth specimen gives a very complete view of the frontal region, with a portion of 
the left horn-core still attached. 
Besides these are numerous fragmentary portions of the cranium, all obviously of 
the same character. 
Numerous detached horn-cores, besides those already enumerated, have been noticed, 
all, with the exception of that figured in fig. 7, Pl. XXII., of the same general form 
and character; and from their size, and comparison with those of the existing Spanish 
and Alpine Ibex, I should conclude that they have all belonged to females. 
The exceptional form shown in fig. 7.is peculiar by its rapid acumination towards 
the summit; but this would appear to be due to some accidental interruption to its 
development. 
The wide cavernous structure of the interior of the horn-cores, and the peculiar 
radiate arrangement of the cancelli which is seen in numerous instances, are shown in 
fig. 2, Pl. XXII. 
2. Trunk.—Bones belonging to the trunk are extremely rare in the collection, none 
having been met with, except of the pelvis, beyond a few more or less entire vertebre. 
One of the most characteristic of these is an almost perfect axis (figs. 4-6, Pl. XX.), 
distinguished from the corresponding bone in Cervus barbarus (fig. 3) by its shortness. . 
