Discovery reports (1962) Discovery reports discoveryreports30inst Year: 1962 146 DISCOVERY REPORTS arranged in double spirals meeting at the centre, the total number of turns being six or seven in large stigmata. Some stigmata form unbroken spirals but others are broken at intervals. Radial vessels () numbering up to about twelve originate at the centre of each stigma, some of them passing dorsally and some ventrally to join the corresponding vessels of the adjacent stigmata. The dorsal lamina has an undivided border and becomes gradually wider towards the posterior end of the branchial
Discovery reports (1962) Discovery reports discoveryreports30inst Year: 1962 146 DISCOVERY REPORTS arranged in double spirals meeting at the centre, the total number of turns being six or seven in large stigmata. Some stigmata form unbroken spirals but others are broken at intervals. Radial vessels () numbering up to about twelve originate at the centre of each stigma, some of them passing dorsally and some ventrally to join the corresponding vessels of the adjacent stigmata. The dorsal lamina has an undivided border and becomes gradually wider towards the posterior end of the branchial sac. Gut. The oesophagus is short and curved (Text-fig. 66B, F, oe.), and the stomach (st.) wider than the rest of the gut and about twice as long as wide. Its surface is marked with many low rounded swellings. The intestinal loop is open only at its distal part. The rectum bends upwards and forwards to end below the atrial siphon. The anus (a.) has a two-lipped opening. S. GEORGIA KERGUELEN FALKLAND IS &. PATN SHELF CAMPBELL, AUCKLAND &. MACQUARIE IS ANTC CONTINENT GRAHAM LAND 25 _J_ 50 —1_ 100 -J SCALE # Text-fig. 67. Affinities of ascidian faunas in the Discovery Collections. Four of the corners of the figure represent the four faunal areas: 1, Antarctic Continent; 2, Graham Land; 3, S. Georgia and 4, the Falkland Islands and the Patagonian Shelf. In each area the percentage of species found also in the other areas is indicated by the height of the peak pointing to the other area. Black polygons represent ascidian species. Clear polygons enclosed by broken lines represent sponge species and are based on figures given by Burton (1932). Gonads. There is one gonad on each side of the body, that of the left side lying a little dorsal to the gut, in the secondary intestinal loop. The right gonad (Text-fig. 66A, g) lies dorsal to the renal sac. Each gonad (Text-fig. 66 G) is sausage-shaped or ovoid and consists of the ovary (ov.) extending the whole length of the gonad, and t
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