HETEROHELICIDS FROM THE TURONIAN OF SENEGAL (WEST-AFRICA) WITH PARTICULAR EMPHASIS ON HETEROHELIX-AMERICANA (EHRENBERG)

The foraminiferan Heterohelix americana, first described in the Upper Cretaceous of the United States by Ehrenberg in 1843, was designated b y Cushman (1927a) as the genotype of Heterohelix Ehrenberg. We have fo und, for the first time in Africa, a form close to this rare species i n samples from Rd2 borehole of Western Senegal, together with a large number of other heterohelicids and hedbergbellids of probable early Tu ronian age. Specimens of Heterohelix americana and some accompanying p lanktonic forms are figured, and some of them discussed where this is warranted by differences or even contradictions in the literature.