1 88 THE GREAT BARRIER REEF. 



the mother-of-pearl shell, Melcagrimi mar gar it if era. When of perfect symmetry, these Cup-corals 

 are in considerable demand, for utilisation as card-trays or other table ornaments. The two species 

 named differ from each other most materially in the sizes and the numbers of the polyp-cells, which 

 are developed, exclusively, on the upper or convex surface, and on the growing marginal rim. 

 In Tiirbinaria pcltata they are relatively large and scattered, but in T. patiila they are minute 

 and crowded. The living corallum in the large-celled species is usuall}' of a whity-brown tint, 

 and the associated polyps a purer white, with greenish centres. The tentacles being numerous and 

 simply subulate, the aspect of the corallum, with its extended polyps, is that of a vase thickly studded 

 inside with short-stalked daisies. Occasionall}', as delineated in the Fig. 12 of Chromo plate VIII., 

 the ground colour of both the corallum and the associated tentacles in Tiirbinaria pcltata is a 

 delicate rose-pink. In the smaller-celled Cup-coral, T. patula, the living corallum, represented by 

 Fig. II of the plate just quoted, is more commonly of a light buff or a golden-brown hue, and the 

 polyps, which are similar in form to those of the preceding species, are brilliant yellow. There are 

 varieties of this t^'pe in which the corallum is a delicate pink or pale lilac, the polyps being a paler 

 hue of the same tint; while, in other instances, the ordinary, buff-coloured corallum is variegated 

 inside with dull green. The two species of Turbinaria above described are especially plentiful in 

 the Torres Strait district ; but, being inhabitants of the deeper water, they are rarely found on the 

 reefs A third type, Turbinaria cincrascnis, whose coralla commonly begin their existence in the 

 form of a cup, and afterwards develop into variously convoluted, foliaceous expansions, is an 

 essentially reef-growing species, and occurs abundantly in the vicinity of the Palm Islands, and 

 at Stone Island, Port Denison. The colour of the corallum of this type, represented, fragmentally, 

 by Fig. 14 of Chromo VIII., is almost invariably a rich golden-brown, and the polyps, as in 

 T. patula, are brilliant yellow. Turbinaria crater, with small polyp-cells and a thin, widely-expand- 

 ing, corallum, is a third species that was obtained by the author from the Palm Islands reefs. 

 The last genus on the list of the Madrcporaria perforata is that of Astraeopora. The polyps 

 in this genus closely resemble those of Turbinaria ; but the corallum is massive, sub-globose, or 

 hemispherical. The polyp-cells are very deep, and devoid of a central columella and conspicuous 

 septa. The colour of the corallum of the typical Barrier species, Astrceopora ptmctifera, is usually 

 a dark brown ; but in one example, collected by the author at the Palm Islands, the base was 

 light yellow, the top half a brilliant lilac-magenta, and the extended polyps rose-coloured. 

 This type is represented by Fig. 13 of Chromo plate No. VIII.; but the lithographic artists 

 have, in this exceptional instance, failed to reproduce the distinct lilac or heliotrope shade that 

 suffused the pink of the upper surface of the corallum, and predominated at the line of junction 

 of the pink and yellow areas here delineated. 



ORDER IV.— ANTIPATHARIA. 



The small order of the Antipatharia represents a group of the Actinozoa, whose position 

 towards the previousl}' described orders of its class corresponds very closely with that of the 



