CORALS AND CORAL-ANIMALS. 183 



the technical title of Madirpora aitstralis. This species is abundantly represented among 

 other luxuriant allies in the photographic reef-view reproduced in Plate XVII., and also by 

 a single typical coralium in the centre of the " Stags'-horn " reef in Plate XII. of the same series. 

 As there shown, the characteristic growth form of this tj'pe is that of a symmetrical bouquet, 

 elevated and erect on a tapering footstalk. The evenly developed branchlets which form the 

 crown of the bouquet, are of considerable thickness, an inch or more at their bases, tapering evenly 

 to their distal terminations, and are but rarely subdivided. The terminal polyp cell of each 

 branchlet is considerably larger than the others, and may be as much as a quarter of an inch in 

 diameter ; corallites of this size very seldom occur among the members of the genus Madrepora. 

 The colours of the living coralla of this species are subject to considerable variation, but are 

 in all instances conspicuously brilliant. A light cream or buff coloured base, with delicate 

 lilac or heliotrope shades extending through the terminal inch or so of each constituent branchlet, 

 represents the most ordinary colour pattern. Sometimes the base is reddish-brown, and the 

 terminal corallites adjacent are a deep purple ; or the coralium may be entirely bright lilac. 

 The extended polyps in all the varieties above enumerated were lilac throughout, those 

 in the terminal or distal regions being the brightest. The tentacles in this species are of 

 uniform size, there being no abnormally long one as obtains in Madrepora hebcs, cotivcxa, and 

 prostrata. Two of the erect digitiform branches of a species, Madrepora ganniifcra, very nearly 

 allied to M. aitstralis but of a yet more robust growth, are delineated in their natural 

 living colours in Figs. 9 and 10 of Chromo plate IX. A fine coralium of this variety, growing 

 in situ, occupies the foreground to the left in Plate XVII. of the photographic reef-views. In 

 addition to the colour variations above enumerated, the coralium of Madrepora gemmifera is 

 not unfrequently brilliant lilac or magenta throughout. 



One other representative of the corymbiform section of the genus Madrepora invites brief 

 notice. This is a species, Madrepora snrcii/osa, very generally included among the stock forms 

 that are commercially collected and exported in a bleached condition for decorative purposes. 

 The shape generally assumed by the coralium of this type is that of a shallow, widely-expanding 

 vase or epergne, the upper, concave, surface of which is thickly beset with short, slender, sprig- 

 like, calicle-bearing processes, which are homologous with the conspicuous terminal branchlets in 

 the several species previously enumerated. A remarkably fine example of this highly characteristic 

 type, associated with smaller specimens of the same species, is included in the photographic reef- 

 view reproduced in Plate XIII. a (No. 2). As with most other species of its genus, the living coralla 

 of Madrepora sitrciilosa are subject to a wide range of colour variation. Some examples, among 

 the more noteworthy of the colour patterns recorded, were a light primrose-yellow throughout. 

 In a second instance, the base and substratum of the expanded crown were pinkish-buff", and the 

 terminal areas of the sprig-like branchlets, with the outer rim of the entire vase-like expansion, straw- 

 colour. In a third, and perhaps more commonly recurring, variety, the general ground colour was 



