186 PONGO 
form found in that particular section of Borneo. It must be borne in 
mind, however, that the part of Borneo from which Herr Selenka 
obtained his material is a very limited area of the island, entirely too 
small to possess any considerable number of species of Ourangs, 
especially as it is well covered with forests through which the Apes 
could travel as they chose, and there are no ranges of lofty mountains 
to act as barriers to their progress. Yet in this comparatively small 
district he describes seven races as distinct, viz.: P. s. landakensis, P. 
s. batangtuensis, P. s. dadappensis, P. s. genepaiensis, P. s. skalauensis, 
P. s. tuakensis, and P. s. rantatensis. Of these batangtuensis was 
supposedly previously described, and the remainder are all antedated 
by Ponco pycmzus Hoppius for the reasons hereafter given. After 
a careful examination of these skulls, (no skins being available), and 
witnessing the almost incredible variations exhibited, and which are 
not confined to any locality, skulls from the same place differing as 
greatly from each other as they do from those in another district, and 
finding no character common to all of them, or even to a few of them, 
which can be regarded as indicating specific distinction, I was forced 
to the conclusion that these variations are simply individual, and may 
not in any degree be regarded as indicating a specific value. I could 
find nothing in this large series of crania which would distinguish 
those of one district, as a whole, from those of any other, and if a 
cranium from one locality exhibited some marked difference from 
others from another place, it would be found that its mate from the 
same district would not agree with it in this particular point. Failing 
therefore to discover any cranial character by which any kind of 
distinction could be established, I was obliged to conclude that but 
one species of Ourang was represented in this collection from Borneo. 
With regard to the cheek callosities, found only on old adult 
males, I do not believe these indicate a specific character, or are even 
dimorphic, as the Hon. Walter Rothschild has considered them to be 
in his paper. It has been proved that Ourangs with and without 
callosities are found in the same district, Selenka so states, and material 
otherwise received from Borneo confirms the fact. It is not to be 
believed that two distinct forms inhabit the same range of country 
characterized only by the presence or absence of these peculiar for- 
mations. It is not reasonable to think so. Then callosities are confined 
to some old males only, and among these, such growths vary greatly 
in size. The skulls, as I have said, give no indication either of the 
presence or absence of these callosities, and if one had to depend 
upon them alone, he would be totally unable to know in which group 
