ALBERT

Beschreibung: Tests of planktonic foraminifera are clastic particles from an off-shore source area, shoreward deposition of which is controlled by sedimentary processes. In Recent sediments, significant correlation was observed between depth and per cent of planktonic tests. Islands had a marked effect on the distribution. In fossil sediments, the varying per cent of tests may assist in locating the former strand line, direction of deepening, and possible off-shore topographic anomalies.

Beschreibung: The Recent brackish-water foraminiferal faunas of the river estuaries and mangrove swamps of Trinidad are described briefly, and notes on the distribution of species are given. Comparable brackish-water faunas of Miocene and Pliocene age are outlined, and some of the species they have in common with the Recent faunas are described. Comparisons are drawn, where possible, between conditions of deposition of fossil and Recent faunas.

Beschreibung: An account of the micropaleontology of the deep-sea sediments deposited in the various zones of the Tethyan geosynclines during the Jurassic and Cretaceous is presented. The study has been considerably hampered by lack of material. Most of the sediments studied came from the present western Mediterranean zone. In general, during the Jurassic (Tithonian) and Lower Cretaceous, radiolarians and globigerines predominated in the zones of subsidence, while Nannoconus and tintinnids were most abundant in the sediments of the deeper zones. Pithonella and Globotruncana predominate in Middle and Upper Cretaceous lithofacies.

Beschreibung: Distributions of the species of Foraminifera (living and dead) forming the greater part of the foraminiferal faunas in marshes in Poponesset Bay, Massa- chusetts, have been studied. Eight stations were sampled bimonthly for one year (August, 1956 to September, 1957). The marsh environments vary from almost non-marine (with tidal influence) to near marine. Arenoparrella mexicana, Haplo- phragmoides hancocki, Tiphotrocha comprimata, and Trochammina macrescens de- crease with increasingly marine conditions, whereas Jadammina polystoma and Trochammina inflata increase. Other species such as Ammobaculites dilatatus, Am- motium salsum, Miliammina fusca, and Protelphidium tisburyense fluctuate inde- pendently of the degree of brackish or marine conditions. Unknown factors govern- ing micro- and macroenvironments probably play an important part in controlling distributions. Suggested factors are type of vegetation, chemical factors, pH, nutrients and food. Calcareous specimens are rapidly destroyed after death pre- sumably due either to the ability of the living form to resist acidity or to a postu- lated increase in acidity immediately below the sediment surface, more probably the latter. This destruction of the tests is of importance in the interpretation of ancient marsh environments. Many species, including the calcareous ones, had their largest living populations in June or September and their smallest in December or February. There were some exceptions such as Miliammina fusca which showed an increase in winter. The total living populations were greatest in June and lowest in December, which may be related to maximum temperature and time of greatest reduction in temperature respectively. Multiple sampling showed that distribu- tions at any one station were fairly uniform although nearby samples in different microenvironments in some cases vary considerably.