MAMMIFERI 5 
The skull of the young H. glaber is smooth and rounded above, 
without any trace of sagittal or lambdoid ridges, these being 
already clearly defined in H. phillips, and the sutures are all 
clearly visible. As to the teeth, m* is not up either above or 
below, but can be seen lying within the bone, thus contrasting 
with H. phillips’, in which the most careful search has failed 
to show any trace of a third tooth, either in front of or behind 
the fully developed and well-worn pair figured in.my paper. 
As to structure it is difficult to find any great difference 
between the upper molars of the two species, but it is probable 
that the external infolding of the enamel extends further vertically 
in the larger than in the smaller form, as in the type-specimen 
of the latter, not I think really so old as the adult H. glaber 
before me, it is almost entirely gone, while it is still persistent 
in glaber. In the lower molars there is more difference, those 
of H. phillips: being somewhat hour-glass shaped, while those 
of H. glaber ave more quadrangular, but in the absence of po- 
sitive knowledge as to which of the latter's three teeth the 
former’s two should be homologized with, it is difficult to make 
any proper comparison. 
The present examples of H. glaber give me an opportunity 
of comparing the lower jaws of the two forms, which I had 
not been able to do before, owing to the loss of this part in 
the Frankfort type. Now that the two are laid side by side, a 
very marked difference is visible in the shape and size of the co- 
ronoid process, which in H. phillips: is simply conical, and so short 
as barely to reach a line drawn from the condyle to the tip of . 
the incisor, while in H. glaber, both adult and young, it is long, 
far surpassing the same line, and strongly hooked backwards. 
This difference will at all ages readily distinguish the two 
species. 
The geographical distribution of the two forms is somewhat 
peculiar, since it appears that H. phillipsi occurs in the very 
middle of the range of H. glaber, this latter being found in Shoa, 
and, as the Italian explorers have shown, over the whole of 
