Three hundred twenty-eight samples from one outcrop of gray marine shales of the Lower Trent River Formation of Eastern Vancouver Island yielded a population of 115,000 Upper Cretaccous Foraminifera consisting of 59 species belonging to 42 genera.

Although the 328 sample suites could not be separated into paleoenvironments by the use of calcareous benthonic/agglutinated ratios, computerized factor analysis explained 85 per cent of the data in terms of five factors, each of which has a definite paleoecological interpretation. Factor one is characterized by the abundance of planktonic species and Gaudryina spp.; it can be considered an inner continental shelf assemblage. Factor two is dominated by Trochammina spp.; it is a typical brackish water fauna. Factor three is interpreted as a mixture of factors one and two. Factor four is characterized by an abundance of Bathysiphon spp., Ammondiscus spp., and Dorothia spp.; it appears to have originated under turbid conditions. Factor five contains a large percentage of Nodosarids and planktonic species; this factor can be considered a deep water marine microfauna.

The spatial relationships of these factors both support the above interpretations and demonstrate the presence of seven sedimentary cycles. The better

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developed of these cycles involved transgression to the extent of attaining deep water conditions followed by regression. Most cycles are bounded by siltstone beds.

Thirty-five newly reported species are described and figured. The presence of Globotruncana concavata indicates that this microfauna is Santonian in age.

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