. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. ON THE LANCELETS OF SOUTH AND EAST AFRICA 263 fin is rather small and lacks the subterminal indentations in outline present in B. capense. The anus is situated in advance of the centre of the lower lobe of the caudal fin. The preanal fin is long but comparatively narrow and the preanal chambers extend almost the full width of the fin. Seen from the ventral aspect the preanal fin chambers are broad and, in some specimens, there is incipient doubling of the fin either at the anterior end only or throug
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. ON THE LANCELETS OF SOUTH AND EAST AFRICA 263 fin is rather small and lacks the subterminal indentations in outline present in B. capense. The anus is situated in advance of the centre of the lower lobe of the caudal fin. The preanal fin is long but comparatively narrow and the preanal chambers extend almost the full width of the fin. Seen from the ventral aspect the preanal fin chambers are broad and, in some specimens, there is incipient doubling of the fin either at the anterior end only or through- out its entire length. The presence of a double preanal fin has been mentioned by Gilchrist (1923) as a character of B. bazarutense. The anterior end of the body is slender and the oral hood comparatively shallow dorso-ventrally. In all the specimens examined well-formed gonads were present. The body is more or less circular in cross-section in contrast with the marked lateral flattening of most species other than B. belcheri. JK. BRANCHIOSTOMA BELCHERI CPORTUGUESE EAST AFRICAN SAMPLC) Fig. 3. These Portuguese East African lancelets agree in all characters with B. belcheri and do not differ very greatly from B. bazarutense. The occurrence of B. belcheri on the coast of East Africa is of special interest as this species seems to be predominantly an Asiatic form. It has already been mentioned that Franz (1922) recorded B. belcheri from a locality near Zanzibar, but that this record badly needed confirmation. The present collection from Linga-linga and Mozambique Island provides that confirmation and suggests that B. belcheri is probably well established on the East African coast as a distinct population. To determine how far the East African form differs from the Asiatic members of B. belcheri, a comparison is made between the Linga-linga sample and another from Amoy on the coast of China, a statistical analysis of which has already been published (Webb, 1956). In Table IV, fr
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