THE 
GEOLOGICAL MAGAZINE. 
NEW. SERIES «) DECADE! ll VOLE. Ve 
No. XII.—DECEMBER, 1888. 
Om EGAN PASE, (ACES ies. 
EAL Ee adel 
I.—NortTE on THE ORBITOIDAL LIMESTONE oF NortH Borneo. 
By A. Vaucuan Jennines, F.L.S, 
Assistant in the Geological Department Normal School of Science and Royal School 
of Mines, 
(PLATE XIV.) 
ee specimens which form the subject of the present note were 
brought to England by Mr. H. T. Burls, A.R.S.M., F.G.S., 
late Geologist to Rajah Brooke, of Borneo. 
It was Mr. Burls’s intention to communicate to the GroLoGgicaL 
Magazine the results of his observations in North Borneo, and in 
this connection I undertook the examination of the limestone with 
a view to obtaining evidence as to its age. On his departure for 
South Africa, Mr. Burls left the specimens at the Science Schools, 
asking me to make what I could out of them without stratigraphical 
details. 
Under these circumstances the present communication has only 
the value of adding a few particulars to our knowledge of one of 
those limestones in the Dutch East Indies which have been loosely 
grouped together as Nummulitie. ° 
The rock is a hard, compact, partly crystalline limestone, with 
specks of iron oxide and thin streaks of calcite, showing little trace 
of organic structure on a freshly broken surface, and altogether one 
that from its physical characters might readily be supposed to come 
from a formation of much earlier date. 
Two specimens, which I understand to be from Silungen in Soubis, 
are of a brown colour, and differ from the others in the species of 
Orbitoides that form their chief organic constituent. 
The remainder from Batu Gading, a locality considerably further 
inland, to the south, are pale grey in colour, and, where partly 
polished by the action of running water (having been collected in a 
stream-bed), show sections of thin Orbitoides discs in great numbers. 
Under the microscope both rocks are seen to consist of a granular 
calcareous ground-mass, in which numerous more or less perfect 
organic remains, chiefly of Foraminifera, are embedded (Pl. XIY. 
Fig. 2). These and the cracks and interspaces of the rock are filled 
in with crystalline calcite. 
After boiling in acid an insoluble residue is left, consisting of fine 
argillaceous material, with a considerable number of minute quartz 
DECADE III.—VOL. V.—NO. XII. 34 
