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Show 1 881.] THE SURVEY OF H.M.S. 'ALERT.' 57 The erect portion of the cell appears to be obscurely annulated, a very slight annular depression connecting the serially arranged puncta. A. somewhat injured dry specimen on indurated clay. Hab. Lat. 50° 35' S., long. 66° 31' W . (open sea off S.E. Patagonia), 58 fathoms. LICHENOPORA GRIGNONENSIS, Busk. (Plate VI. fig. 2.) Tubulipora grignonensis, Milne-Edwards?, Mem. Tubulipores, Ann. Sci. Nat. (2) viii. p. 333, pi. xiii. fig. 2. Discoporella grignonensis, Busk, Crag Polyzoa, p. 116, pi. xx. fig. 4. Lichenopora, Defrance; Hincks, Hist. Brit. Mar. Polyz. p. 471. Zoarium simple, closely adnate. Lamina very narrow, thin, almost entirely occupied by ridges indicating rudimentary zocecia. Zoarium strongly convex from the centre to the lamina, circular in outline. Zocecia partially arranged in radiating series (the series generally interrupted by the occurrence of intermediate cells) around a small central space ; orifices raised, considerably so near the centre ; the entire front of the peristome wanting, posterior part horseshoe-shaped, margin obscurely roughened; sides faintly ridged longitudinally, and bearing from three to about ten scattered delicate pointed spines not exceeding half the diameter of the cell in length. Interspaces between zocecia and the central area crossed by a network of trabeculae, enclosing polygonal spaces with rounded angles; those between the zocecia vary in diameter from one half the breadth to the same breadth, that of the orifices of the zocecia, those in the centre varying from that diameter to twice its size, and partially tympanized by a calcareous septum with a central perforation; also from the points of junction of the trabecular which form them projects occasionally a slender spine like those on the walls of the zocecia. Ocecial orifice slightly raised, being surrounded by a thin, narrow, forwardly sloping rim perforated by a single circle of about six small punctures ; diameter of opening about twice that of a zocecium ; margin finely dentate. Hab. Sandy Point, 9-10 fathoms, on piece of a Selachian's egg. Four colonies occur, representing three different stages, the latest with fifty-three or more well-developed zocecial openings, the earliest with only about a dozen openings, scarcely raised above the general surface, the lamina being about twice as broad as in the oldest specimen. In this young specimen, too, the cancelli have hardly appeared, the surface between the cells bearing only an occasional puncture. The development of the spines can be traced from a stage in which they are mere short blunt tubercles to that in which they have the adult proportions. It is also interesting to note that in the same stage (the middle one of the three here represented), in which the zocecia are 2 millims. in greatest diameter, the longitudinal ridges, so indistinct in the oldest specimen, project boldly from the zocecial wall and sometimes form prominent crenations on the margin. The three young colonies have a somewhat oval outline; the older |