507 
Lastly J. CHAPMAN ') recorded the occurrence of Halimeda in “Late 
Caenozoic reef-rock”’ of Malikolo, New Hebrides, and (reproduced a 
limestone), almost entirely composed of fragments of Halimeda. In 
other places Halimeda never seems to have occurred as a rock- 
builder *). 
It is a fact, therefore, that in Europe Halimeda is encountered in 
Tertiary rocks, while in East-Asia and in Australia it is found up 
to the present only in very late reef-deposits, which have been formed 
in the Quaternary or on the boundary between Quaternary and 
Tertiary. 
Some years ago [ found in Old Miocene marls, scattered largely 
to the west of Bontang, on the Kast coast of Borneo, small flat 
calcareous bodies, which were not determinable. A few years later 
I saw on the coast-reef north of Wahai, Central Ceram, plants of 
a green alga, whose elements very much resembled the Borneo 
fossils. The Wahai alga appeared to belong to Halimeda Opuntia 
Lam and the Bontang fossils seemed to possess all the external and 
the internal characteristics of the genus. While investigating the 
silt-material from Old-Miocene marls of other finding-places in East- 
Borneo, still more Halimede were detected, rare specimens in an 
Old-Miocene marl from Sg. Blakin on the West-side of the Balik 
Papanbay and very numerous specimens in an Oligo Miocene mar! 
Fig. 1. > 2,2. Halimeda cf. Opuntia Fig. 2. & 9 (longitudinal section). 
Lam. forma triloba. Old- Miocene mar]. Bontang. 
1) J. CHAPMAN. Australasian Fossils. 1914, p. 77. 
*) E. GARWoop. On the important part played by calcareous algae at certain 
geological horizons. The Geol. Magazine. (5). X. 1913. Nos. 10, 11, 12. 
