Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . sented by Mr. Paterson(SAM 24524). All three were a dirty grey-green dorsally with a white , anal and pectoral fins were pale yellow. The pectoral fin has a charac-teristic shape, being broad, rounded on the lower distal corner, and pointedat the upper. The species is capable of very extensive inflation and all threeexamples examined were much distorted due to this. Zoogeography The relative geographical positions of the islands of Tristan da Cunha,Gough, St. Paul, Marion and Crozet, the Vema Seamount and
Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . sented by Mr. Paterson(SAM 24524). All three were a dirty grey-green dorsally with a white , anal and pectoral fins were pale yellow. The pectoral fin has a charac-teristic shape, being broad, rounded on the lower distal corner, and pointedat the upper. The species is capable of very extensive inflation and all threeexamples examined were much distorted due to this. Zoogeography The relative geographical positions of the islands of Tristan da Cunha,Gough, St. Paul, Marion and Crozet, the Vema Seamount and South Africaare shown in figure 2. Tristan, Gough and St. Paul islands lie on very similarlatitudes, whereas the Vema Seamount is roughly as far north of Tristan as theMarion and Crozet groups are south. The Vema Seamount, however, hasseveral fish in common with Tristan whereas the Marion and Crozet groupshave no fish in common with Tristan or St. Paul. This, as was suggested bySivertsen (1945), is almost certainly due to hydrographic conditions, mainlywater Fig. 2Shallow-water areas in the southern Atlantic and Indian Oceans. 542 ANNALS OF THE SOUTH AFRICAN MUSEUM There are two areas of sudden temperature change in the Southern Ocean,the Sub-Tropical Convergence, where the surface temperature rapidly changesfrom about i3°C to about g°C and a more southerly line, the Antarctic Con-vergence, where the surface temperature again drops, from 6°C to about 2° Antarctic Convergence is quite narrow but the Sub-Tropical Convergenceis much broader and Sverdrup et al. (1942) refer to it as a Region of Conver-gence. The Sub-Tropical Convergence fluctuates in latitude, at times the wholezone is 5-60 South of the Island and at other times Deacon (1937) suggeststhat it may be north of Tristan. Temperatures taken at Gough Island at a timewhen he suggested this do not support it, however. Gough Island is approximately 30 20 south of Tristan, thus it may lienorth or south
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