THE AUSTRALIAN GREAT BARRIER REEF. 105 



upon which the most violent storms, of hurricane force, strike the reefs during the prevalence 

 of tiie north-west monsoon. 



The extreme edge of Westari reef, having its position indicated by rippling waves, in 

 Plate XXX., is very ragged and precipitate, and hollowed out into deep gulches, from which, 

 probably, the stranded rock boulders in the foreground were originally torn. The reef-rock 

 itself is full of " potholes," sometimes several fathoms deep ; and among them it is necessary 

 to tread circumspectly. These hollow potholes teem with brilliantly-coloured and grotesquely- 

 shaped fish of innumerable varieties, constituting veritable aquaria with side walls composed 

 chieflj' of living corals of various tints. In photographs taken nearer the edge of the reef, 

 when the tide was a foot or two lower, its surface is shown to be covered to a considerable 

 extent with the growing coralla of two corymbiform species of Madrepora, pronounced by 

 Mr. G. Brook, F.L.S., to be Madrepora prostrata and a variety, compada, of Madrepora inillepora. 

 Other species of the genus, collected during an hour or so's exploration of this and the neigh- 

 bouring " North-West " reef, included, as identified by the above-named authority, Madrepora 

 hcbes, friiticosa, dccipieiis, geminifera, seriata, pcctinata, surculosa, variabilis, sariiieiitosa, reeuinbeiis, 

 bmodadyla, digitifera, with Madrepora (Isopora) palifera and cuneata. In addition to these, a host 

 of Astraeaceae and other Madreporaria that yet await identification were obtained. The 

 growth habit of the last-named species of Madrepora, M. cuneata, is peculiar. This species, 

 with a few other varieties, has been referred by Dana to the sub-genus Isopora, on account of 

 the fact that the subdivisions of the coralla are not associated with a single, usually larger, 

 terminal, or growing, corallite, as is usual among all the ordinary representatives of the 

 genus. In this particular species, M. cuneata, the coralla on the Westari and the North- 

 West reefs are encrusting forms, spreading out in ridges from a central point over areas of the 

 platform-reef, which, having a thin sheet of water flowing over them from the inner lagoon, 

 at even the lowest tide, are thus continually submerged. In deeper water on Westari 

 reef, the same species of coral, in company with Madrepora palifera, forms robust, erect 

 folia, of considerable dimensions. The life-colours of the coralla of this species are not so 

 attractive as those of many of the members of the genus. They are chiefly light buff in hue, 

 but variegated, to the extent of the edges of the corallites and their contained polyps being 

 lemon or primrose colour. 



The beach near high-water mark of North-West Island yielded many specimens of interest 

 that had been thrown up from deep water in heavy weather. These included the remarkable 

 flexible coral, his liippuris, a representative of the Gorgoniaceae, in which the corallum is composed 

 of alternate joints of black horn-like and white calcareous matter, which will be found illustrated 

 by Chromo plate XL, Fig. i. A red Hydroid coral, Disticlwpora coccinca, and the Black coral, 

 Antipathes abies, both of which are delineated in the same plate, together with some very fair 

 examples of sponges, having as fine a texture as many of'the ordinary commercial species, were 



