. Text-fig. 45. Pyura discoveryi (Herdman) (St. 474): A, specimen with long siphons; B, the same with test removed; C, dorsal tubercle; D, oral tentacle; E, hepatic tubules; F, showing position of left gonad (St. 1948); G, right gonad of same specimen. Siphons. According to Kott (1954) there are no spines in the lining of the siphons, and I also can find none. Tentacles. The tentacles number sixteen to twenty and are only slightly branched (Text-fig. 45 D). Dorsal tubercle. The opening of the dorsal tubercle is basically U-shaped with the ends of the limbs variously bent; usually both are turn
. Text-fig. 45. Pyura discoveryi (Herdman) (St. 474): A, specimen with long siphons; B, the same with test removed; C, dorsal tubercle; D, oral tentacle; E, hepatic tubules; F, showing position of left gonad (St. 1948); G, right gonad of same specimen. Siphons. According to Kott (1954) there are no spines in the lining of the siphons, and I also can find none. Tentacles. The tentacles number sixteen to twenty and are only slightly branched (Text-fig. 45 D). Dorsal tubercle. The opening of the dorsal tubercle is basically U-shaped with the ends of the limbs variously bent; usually both are turned outwards, or the left one outwards and the right one inwards, or one or other may point forward (Text-fig. 45 C). Branchial sac. Some authors have said that there are six branchial folds on each side (Herdman, 1910; Hartmeyer, 1911; Kott, 1954) and others that there are seven (Sluiter, 1914; Arnback, 1938; van Name, 1945). In all the specimens from the 'Discovery' collection that I have examined there are seven folds, and although the ventral fold is lower than the others, it is unmistakably present. This finding agrees with Arnback's careful review of the question (see Arnback, 1938, pp. 30-2). In
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