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chambers are already rhombus-shaped. A primary lamella can never 
be distinguished at the parietes. Radial diameter of the peripheric 
chambers 100 u tangential 90 «. At thicker spots in the preparations 
one sees very distinctly the wide vertical pori going to the lateral 
chambers. 
Vertical section. There is only one stratum of median chambers. 
In vertical section this stratum is rather slightly strung at the 
extremities of the chambers. On either side of it are 5—6 strata of 
lateral chambers, which are very flat and placed on each other some- 
what in the way of scales. The thickness of the fossil is 0.8 mm. 
Besides the Foraminifera mentioned I found in the marl of the 
Sungei Blakin: Operculina spec., Amphistegina spec. ? Cycloclypeus 
spec., and other Foraminifera, which I could not determine. 
The third place where numerous Orbitoides could be gathered, 
lies on the upper-course of the Sungei Mentawir in strata that are 
certainly younger than those on the Sungei Blakin and that most 
likely, towards the top gradually pass into the pliocene strata, very 
rich in coal, which occur everywhere in the lower, part of the Balik 
Papan Bay. 
O (Lepidocyclina) sumatrensis Brady, var. minor nov. var. 
Most numerous is here again a very small Orbitoid agreeing in 
nearly every respect with O. sumatrensis of the Sungei Blakin. The 
principal difference consists in the fact that the sort on the Sg. Men- 
tawir is considerably smaller (d 1'/,—2, h 1, 2—8'/, m.m.) This 
cannot be accidental, because we should have gathered from this 
place only the smallest varieties: the material gathered in both places 
being much too large. For the further description we can refer 
almost entirely to O. sumatrensis. Only no or hardly any skeleton- 
columns occur with the form of the Sungei Mentawir, which would 
indeed be astonishing with so small a form which by its globosity 
possesses already a natural maximal solidity. 
QO. (Lepidocyclina) neodispansa Jones and Chapham, var. 
minor, nov. var. 
I can dispose of about 20 specimens of this form tallying very 
well with one another. In general these have again great resem- 
blance to O. neodispansa. The disk is gradually thickened towards 
the middle and a number of comparatively large warts (max. 20 
