Appendicularians from 41 vertical hauls (200-0m) made during the 5th cruise of' ‘Anton Bruun’ in the central part of Indian Ocean, have been examined. 16 species in 4 genera have been determined among 9098 secimens. The Oikopkwidae represent 88 % of this number and may be found in all the samples. The Kowalevskiidae being always absent, the Fritillaridae account for 12% but did not appear in 12 hauls. O. longicauda is the most abundant species, with 60% of the total number of appendicularians collected. Then follow: O. cophocerca 9%, O. rufescens 8.5%, F. borealis 7%, Meg. huxleyi 4%, O.fitsiformis 3% and F. formica 2%. None of the other species exceeds 2%.

A very important variation of the average number of the appendicularians with latitude is observed. From 42°S to 20°S it is not greater than 24 individuals. From 20°S to the equator it stands between 100 and 175. In the northern hemisphere there is a very important increase and the average passes to 475 and then to 600 individuals. The variation of the number of species is different and has also a minimum (1) in the south, the maximum being between 20°S and 10°S.

The quantitative geographical variations of the most abundant species are studied; finally the differential distribution of the Appendicularia is analysed in relation to the currents and the water masses.