A. V. Jennings—Orbitoidal Limestone in N. Borneo. 531 
O. (Discocyclina) applanata, Giimbel.,! Pl. XIV. Fig. 3a, 8, ¢, d. 
While the Silungen limestone contains the thicker, more lenticular 
forms mentioned above, the specimens from Batu Gading are full of 
a thin, discoid, umbonate species apparently the O. applanata of 
Giimbel. In vertical section they are seen to possess a median 
plane of rectangular chambers, and only three or four layers of 
lateral chambers on each side, except at the central umbo. The solid 
columns are not prominent. Numerous horizontal sections evidently 
of the same form show that the chambers of the median plane are 
rectangular and narrow, the radial measurement often four times the 
tangential. This character, together with the shape, would seem to 
decide its position in this species. Giimbel mentions its occurrence 
in Scinde. 
O. (Asterocyclina) stellata, Giimbel.? Pl. XIV. Fig. 7. 
The stellate Orbitotdes included by Dr. Giimbel in this subgenus 
have a sufficiently characteristic appearance when cut horizontally 
to admit of recognition even in a rock section. One of them occurs 
in the Batu Gading limestone, and is apparently a young form of 
this species. 
O. (Lepidocyclina) Mantelli, so abundant elsewhere, does not 
appear to be present, nor any of the Rhipidocycline species. There 
are several small thick forms of the size of O. Sumatrensis, Brady,? 
but they have large embryonic chambers, and seem to be young 
forms of other species. 
Nummulites itself seems to be absent. 
The only other fossil is a coral in the Silungen limestone, which 
Prof. P. Martin Duncan has kindly examined, and refers to the genus 
Stylophora (Pl. XIV. Fig. 1). As this is a common type through- 
out the Tertiary rocks, its occurrence is of little stratigraphical value. 
With regard to the age of the Orbitoidal limestone, there is little 
to be said until more is known of its position and stratigraphical 
relations. 
The limestones and associated beds of Java have been doubtfully 
regarded as Eocene, an opinion supported by the resemblance of 
their Molluscan fauna to that of the older European Tertiaries. 
According to von Richthofen,* however, the associated plant-remains 
pointed distinctly to their being at the oldest Miocene, and this 
view was supported by the discovery that what had been taken for 
Nummulites were Orbitoides, and by the suggestion, so strongly 
enforced by Dr. Duncan’s examination of the Scindian Corals,> that 
parts of the Indian ‘ Nummulitic’ formation were probably Miocene. 
It is worth noticing also that in Sumatra® the Orbitoidal limestone 
occurs at the top of a series of Tertiary beds. 
Op. cit. p. 122, pl. 3, figs. 17, 18, 35, 36, 37. 
Op. cit. p. 135, pl. 2, fig. 115; pl. 4, figs. 4-7. 
Op. cit. p. 536, pl. 14, fig. 3. 
See H, M. Jenkins’ Summary, Q.J.G.S. vol. xx. 1864, pp. 62-72. 
See Palontologia Indica, ser. xiv. vol. i. pt. i. Sind Fossil Corals, 1880, pp. 3-14. 
Verbeek, Grou, Maa. 1875, p. 479. : 
aonrF WON 
