3S 
THE MAMMALS OE EGYPT. 
the great Lake Victoria Nyanza. They also extend through the river-system of the Bhar- 
el-Ghazal to Bar Fertit, vrhere Schweinfurth obtained specimens. From the Victoria 
Nyanza district this species possibly follows the greater part of the river-system of the 
Congo, while from Bar Fertit it extends to the Niger. Its form seems to be modified 
in given areas of this vast region, but the differences manifested in the scanty material 
at present available will probably be somewhat bridged over when zoologists are 
placed in full possession of the different phases assumed by the individuals in diverse 
geographical areas and at various periods of their existence. 
The skull of this baboon has a heavy and deep muzzle, sloping forwards and slightly 
downwards to the end of the nasals, beyond which it curves downwards and forwards. 
(See Plate V. for side view of type of P. heuglini.) The orbito-maxillary ridge is 
well-defined, but the surface between these ridges varies somewhat, depending on the 
character of the nasals, as in some specimens these bones form a slightly rounded 
longitudinal mesial eminence with a slight concavity external to them on either side, or 
a flattened surface. In other skulls the nasals may not be raised, but may be somewhat 
concave at their middle antero-posteriorly, with a marked lateral longitudinal depression 
on either side of them. These characters are present in both males and females. The 
skull from Shilluk has raised nasals with a concavity on either side, while in the baboon 
from Abyssinia, collected by Buppell, these bones are less raised, and the lateral 
areas external to them are nearly flat. In the male from the Gash River the nasals 
are slightly concave at the middle. The nasals vary in breadth anteriorly and 
posteriorly. When they are broad before their suture with the frontal, they gLe rise 
to a broad interorbital septum, as in the baboon from the Shilluk Islands (Plate V. 
fig. 1) ; and when less so, to a narrow septum such as occurs in the skull from 
the Gash River (Plate VI. fig. 1); whereas in the skull from Abyssinia the breadth 
of the septum is intermediate between that of the two foregoing skulls. 
The following are the measurements of this septum in four male skulls authenticated 
by their skins:— 
Nile baboon. Stuttgart Museum . . 
Nile baboon. Darmstadt Museum . . 
Abvssinian baboon. Erankfort Museum 
Abyssinian baboon. Munich Museum 
Length of skull, 
mm. 
218 
213 
228 
209 
Breadth of septum, 
mm. 
14 
10 
11 
12 
It seems evident that no importance can be attached to these variations in the 
breadth of this septum in these four skulls ; but at the same time it is an interesting 
fact that in the skull of a large male baboon obtained by Schweinfurth from Dar 
Fertit, on the watershed of the Nile and the Congo, this septum is broad. This 
