738 
grey to blue, clayey and clayey-sandy, and the strata are for the 
greater part very imperfect; they often contain bulbs and strata of 
dense, grey, yellowishly disintegrating marl-limestones. The limestones 
are partly coralligenous rocks, partly very remarkable lime-sandstones 
poor in fossils; quartz conglomerates of hornstone with a very 
abundant cement of calcite; analogous rocks occur likewise in the 
above described coralligenous limemarlfacies of the Sekerat Mountains. 
The marls which are very rich in fossils are grey, often very sandy 
and can easily be separated; they contain besides Globigerinidae 
many littoral Foraminifera (Amphistegina, Operculina, Cycloclypeus 
and in lower strata also Lepidoeyelina) and numerous fragments of 
Jorals, Echinids and Molluses. We shall by-and-by distinguish marls 
of analogous habitus — though they may partly be of a different 
age -— especially on the Batu Hidup and the Gunung Batu anti- 
elinal, in the river basin of the Lower Sampajau. We shall hereafter 
indicate these facies constantly as Sampajau marls. 
On the Northern part of the Eastern limb of the Sembulu anti- 
clinal the superposition of the described strata is thus, that the 
Globigerinaemarls, with a few banks of limestones and Sampajau 
marls lie deepest; then follows a rather thick complex of limestoues, 
limesandstones and gravellimestones, whilst typical Sampajau marls 
lie on the top.-The total thickness — from the lowest Globigerinae- 
marls to the axis of the synclinal between Sembulu and Maluwi 
anticlinal — is here about L200 m. 
In this formation occur moreover on the Upper Lemudjau and the 
Upper Lindak banks of a very remarkable rock — for East Kutei, — 
which we shall meet afterwards on the Southern limb of the Maluwi 
anticlinal in the river basin of the Sungei Mangenai, in about the same 
stratigraphical level. They are white clayey -- sometimes sandy — 
very light voleanie tufas, most likely deposited in an aeolic way. 
Where the rock is fresh, we see in microscopical preparations, 
that the principal mass consists of an entangled conglomerate of 
glass threads, between which mineral splinters of biotite, green born- 
blende not or little twinned feldspar and most likely also quartz are 
found. With the naked eye one recognizes from these minerals as 
a rule only the numerous, idiomorphous biotite scales. The result of 
a determination of siliceous acid that Mr. Mom, assistant at the agro- 
geological laboratory at Buitenzorg, was kind enough to make for 
me, was that a sandy tufa of the Upper Lemudjau contains 72.2°/, SiQ,. 
We saw that the described limy- (calcareous) marly- tuffaceous 
formation in the North of the Sembulu anticlinal rests on the old 
miopliocene ; it must consequently be synchronous with part of the 
