. 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 ba
. 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 the testis (t.) in the form of groups of follicles arranged round the sides and ends of the ovary. There is a single short terminal oviduct (od.) and usually two male openings on short tubes (), arising from the mesial face of the gonad. Renal sac. The renal sac is a short slightly curved body on the lower half of the right side (Text- fig. 66 A, ). Feeding mechanism. The branchial sac contains a mixture of sand grains, small inorganic particles, whole and broken diatoms and small algal cells (PI. VI, fig. 6). Sand grains and most of the other inorganic particles are, however, absent from the stomach and intestine (PI. VI, fig. 7) indicating that there is some sorting mechanism. The mechanism is probably in the oesophagus which appears to accept food particles and reject sand grains and other particles not of food value. The nature of this mechanism is unknown, and its operation does not seem to depend solely on the size of the particles, because diatoms are accepted which are as large as the san
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