Foraminifera from the Bay of Jakarta, Java

Abstract

Foraminifera from the North coast of Java have been described by MILLET (1898-1904); by KEIJZER (1935). The Siboga Expedition did not sample on the Java coast; most of the species described by Millet were also collected elsewhere in the Indonesian Archipelago. Keijzer did not have the intention to describe the faunas he gathered, but he mentions the occurrence of many species at the coast at Rembang, East of Soerabaia and the Strait of Madoera. The list of species described by him is as follows: Cornuspira involvens (Reuss); not found in the Bay of Jakarta. Biloculina vespertilio Schlumberger; idem. Triloculina tricarinata d’Orbigny; found in the Bay of Jakarta. Triloculina trigonula (Lamarck); not found in the B. of J. Triloculina rupertiana (Brady); found in the B. of J. Triloculina fichteliana d’Orbigny; found in the B. of J.; now known as Flintina bradyana Cushman. Spiroloculina planissima (Lamarck); not found in B. of J. Spiroloculina depressa d’Orbigny; not found in B. of J. Spiroloculina grateloupi d’Orbigny; found in B. of J.; given here as S. communis Spiroloculina nitida d’Orbigny; not found in B. of J. Quinqueloculina venusta Karrer; not found in B. of J. Quinqueloculina kerimbatica (Heron-Allen and Earland); found in B. of J. Quinqueloculina seminulum (Linne); found in B. of J.; it is in reality Quinqueloculina bicostata d’Orbigny. Massilina agglutinans Keijzer; not found in B. of J.; this was not a new species, as Keijzer believed, but Pseudomassilina australis Cushman, 1932, as the inner structure proves. Discorbis globularis (d’Orbigny); not found in B. of J. Operculina complanata (Defrance); found in the B. of J. Textularia gramen d’Orbigny; found in the B. of J.; this is Textularia kerimbaensis Said. Textularia agglutinans d’Orbigny; found in the B. of J.; this is Valvotextularia foliacea (Heron-Allen and Earland). Rotalia papillosa Brady; found in B. of J.; this is Rotalidium concinnum (Millet). Rotalia schroeterania Parker and Jones; found in B. of J.; now known as Pseudorotalia. The material studied here was originally collected by the Laboratory for Investigation of the Sea at Batavia, in 1937 and later years (textfig. 1). It was gathered for the study of the molluscs, but the finer residues contained many Foraminifera. As will be seen from the chart, Foraminifera were found mainly in the western part of the Bay of Jakarta; from the Eastern and coastal stations no Foraminifera were collected; this may be a consequence of the low salinity of these parts. The richer faunas were found in the northwestern part; the direction of the current is from west to east, so in this part the salinity will have been high, as well as the concentration of 02. In the eastern part, the salinity must have been low, and much detritus must have been found there from rivers and sewage. From north-west to south-east the samples contain less and less species of Foraminifera, till in the Stations H4,F3,G3, E2 the samples mainly contain many specimens of Pseudorotalia schroeteriana, Asterorotalia pulchella and Elphidium batavum.