Palaeontology. — “On the Occurrence of Halimeda in Old- 
Miocene Coastreefs of Hast-Borneo”. By Dr. L. Rurren. 
(Communicated at the meeting of April 23, 1920). 
In arranging the collections of the Siboga-Expedition it appeared 
how widely the calcareous alga Halimeda of the order of the Siphoneae 
is spread on the coastreefs round the islands in the eastern part of 
the East-Indian archipelago. This organism is found at the coast of 
the Little-Sunda Islands, at several places of the coast of Celebes, 
around the Aru- and Kei-islands and in the Banda-Archipelago *). 
In connection with this fact it is remarkable that up to this day 
so little has become known of the occurrence of this alga, which 
is so well adapted to fossilization, in the tertiary, littoral deposits of 
the East-Indian Archipelago, which have so many features in common 
with the present coast-reefs: as e.g the corals, the lithothamnia and 
the foraminifera, which are the chief builders of recent reefs, are 
also met with in the tertiary coast-limestones. 
To my knowledge R. Scnupert’) is the only writer who has 
reported the occurrence of Halimeda in very young — probably 
quaternary — limestones of North- and Central-Celebes. 
Also out of the East-Indian Archipelago fossil-rests of Halimeda 
have been found very rarely. TH. Fucus ®) was the first to describe 
unquestionable fossils from the Eocene of GruirEnsTEIN ; the Halimeda, 
whose ‘branchlets’ were impressed in sandstone, so that only the 
external form had been preserved, bore a great, habitual resemblance 
to the alga still living. Slight morphological deviations led to the 
establishment of a new species of fossils: H. Saportae. 
In some limestones — “transition rocks between Miocene and 
recent” — of Christmas Island, south of Java, also traces of Halimeda *) 
were found. 
1) E. S. Barton. The genus Halimeda. Monograph LX of the Siboga-Expedition, 
1901. 
2) R. ScruBerT. Beitr. z. fossilen Foraminiferenfauna von Celebes. Jahrb. K.K. 
Geol. Reichsans. Wien. 62. 1912, p. 127—150. 
3) Tu. Fucus. Ueber eine fossile Halimeda aus dem eocänen Sandstein von 
Greifenstein. Sitz. Ber. Akad. der Wiss. Wien. Math. Natw. Cl. Abt. I. 103. 1894. 
p. 200—204. 
4) Gu. W. ANDREWS. A monograph of Christmas Island. 1900, p. 250, 275. 
