2 Dusois—On Pithecanthropus erectus : 
in many places, may have on an average a breadth of from one to three miles. 
They are contained in beds of cemented volcanic tuff, consisting of clay, sand, 
lapilli stone, which especially, through the very general occurrence of the remains 
of freshwater animals, and of that fluviatile structure which English geologists 
call current-bedding, or false bedding, prove to be of fluviatile origin. The strata 
have undergone, in the whole area, considerable disturbances by folding, on 
account of which they have, from east to west, dips of 3° to 15° in a general 
southerly direction. The whole formation reaches a maximum thickness of more 
than 350 metres. The strata rest, unconformably, upon beds of marine marl, 
sand, and limestone, recently determined by Professor K. Martin to be of 
Pliocene age. The fossil vertebrate fauna, which they contain, is everywhere 
in the Kendeng, and also in other places in Java, the same, and a homogeneous 
one. Its age can only be judged when the description of my collection, which 
I intend to give in the course of a few years, shall be published. But I have 
studied it already a little, and it can be said, in accordance with geological 
circumstances, and the relations which this fauna has with the Post-Tertiary and 
Pleistocene vertebrate faune of India, that, most probably, itis young Pliocene; in 
no case, however, can it be younger than the oldest Pleistocene. For, whilst on the 
one hand the species surely belong almost exclusively to living genera—only the 
genus Leptobos and the sub-genera Stegodon and Hexaprotodon are extinct—and 
it must therefore be younger than the principal part of the Upper Miocene or Lower 
Pliocene Siwalik-fauna, including not a few extinct genera; on the other hand, the 
number of the extinct species seems to be in proportion somewhat greater than 
that of the Narbadd-fauna, which is put in the early Pleistocene. Further, 
the inclination which the strata show does not well agree with a Pleistocene 
age. 
In August, 1891, in the neighbourhood of Trinil (in the regency of Ngawi, of 
the Residency Madiun), at the foot of the Kendeng, I came upon a place particu- 
larly rich in fossil bones, and found there, in that and the following year, among a 
great number of remains of other vertebrates, bones and teeth of a great man-like 
mammal, which I have named Pithecanthropus erectus, considering it as a link con- 
necting together Apes and Man. ‘These remains I held to be so important that I 
thought it necessary, notwithstanding the great incompleteness of my resources of 
comparison, to publish a provisional description in Java, especially because, through 
my very short reports given to the Netherland Indian Government, these finds had 
already raised more or less scientific discussions in Europe. It is now a year ago 
since my description came into the hands of the most renowned anatomists and 
zoologists of Europe and America; it gave occasion to so much criticism that the 
great importance of the remains is now unquestionable. But in the interpreta- 
tion of them a very large divergence is also apparent. ‘This divergence may be 
