. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. DESCRIPTION OF SPECIES 85 Occurrence. St. 123: S. Georgia, 230-250111. St. 144: S. Georgia, 155-178111. St. 160: Shag Rocks, 177 m. St. 371: S. Sandwich Islands, 99-161 m. St. WS 27: S. Georgia, 104 m. St. WS 243: Patagonian Shelf, 144-141 m. St. WS 841: Patagonian Shelf, 110-121 m. Colony. The largest specimen in the collection is one from the Patagonian Shelf (St. WS 841), measuring 9 cm. tall, 1-5 cm. thick, and 7 cm. long. The original colony must have been still larger, as the specimen is o
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. DESCRIPTION OF SPECIES 85 Occurrence. St. 123: S. Georgia, 230-250111. St. 144: S. Georgia, 155-178111. St. 160: Shag Rocks, 177 m. St. 371: S. Sandwich Islands, 99-161 m. St. WS 27: S. Georgia, 104 m. St. WS 243: Patagonian Shelf, 144-141 m. St. WS 841: Patagonian Shelf, 110-121 m. Colony. The largest specimen in the collection is one from the Patagonian Shelf (St. WS 841), measuring 9 cm. tall, 1-5 cm. thick, and 7 cm. long. The original colony must have been still larger, as the specimen is only a portion. In form the colonies (PI. Ill, fig. 1) are generally pillar-like, wedge- shaped, or club-shaped and are often markedly flattened from side to side. The test is firm but not hard, sometimes almost clear and occasionally nearly opaque. Some of the colonies from South Georgia and the Patagonian Shelf are reddish brown in colour. In most specimens the zooids are A _ H mm mm. Text-fig. 25. Tylobranchion speciosum Herdman: A, zooid (St. WS 27); B, C, D, branchial papillae from different specimens (Sts. WS 27, 371, WS 243); E, gonads; F, transverse section of zooid at level of heart; and G, below level of heart; H, larva (St. 144). readily visible through the test. Attachment of the colony is usually to a small group of pebbles embedded in the basal test. Zoom (Text-fig. 25 A). The general structure of the zooid is already known, and the principal variations in the ' Discovery' specimens are tabulated on page 86. Certain points regarding the lower part of the zooid, however, have remained doubtful. Berrill (1935) described a true post-abdomen containing the heart and gonads, but Arnback (1927, 1950) showed that the heart is much farther forward than Berrill's figure indicated. A careful examination of the ' Discovery' specimens allows me not only to confirm Arnback's findings, but also to add details concerning the epicardium and the nature of the posterior
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