PHOTOTYPE PLATES NOS. IV. AND V. 



13 



which hang in thick festoons over so large a number of the coralla, are, however, undoubtedly 

 responsible for a very large share of the work of decay and disintegration. 



The outer or seaward edge of this same Palm Islands reef, incorporating a much 

 wealthier variety of coral-growths, finds characteristic illustration in several succeeding plates, 

 among which Nos. VI. and X. may be specially referred to. 



NO, 2.-ER0DED INSHORE REEF, THURSDSY ISLAND. 



This reef-view, at first sight, appears to embody but few points of interest, consist- 

 ing for the most part of dead, much-eroded coral-rock, more or less encrusted with fleshy 

 Alcyonaria, and the calcareous vegetable growths known as Nullipores. This picture is, 

 however, of value, as it constitutes a highly characteristic illustration of a typical foreshore, or 

 platform reef, at that point where the coral ceases to live, and where the rock-mass is almost 

 exclusively composed of the consolidated debris of species formerly growing on the outer 

 margin of the reef A heap of these cast-up fragments, in their as yet unconsolidated state, 

 may, in point of fact, be observed lying between the two large masses of peripherallj'-growing 

 Goniastraeae that occupy the foreground. The higher (or back) portion of the picture represents, 

 in other words, that plane of elevation where corals cannot exist, in consequence of its prolonged 

 exposure to the sun and air with every ordinary ebb-tide. The vital phenomena of the 

 Goniastraeae as depicted in this reef-view are, of themselves, highl}' interesting and instructive. 

 In addition to illustrating the normal vertical growth limits of the species, it indicates the 

 potentiality of the coralla to spread laterally to any unimpeded extent. The general aspect and 

 plan of expansion of the coralla here illustrated may be said to constitute an epitomisation 

 of the growth of the entire reef, pushing forward with vigorous energy on its outer edge, 

 and leaving behind it a mass of loose or consolidated debris with scattered patches of semi- 

 suspended vitality. 



PLATE V. 



NO. l.-MfiDREPORA ISLET, PORT DENISON. 



This exceedingly picturesque reef-view is typical of the coral-growth that predominates 

 over a large area in the vicinity of Stone Island, Port Denison, on the North Queensland coast. 

 Stags'-horn corals, belonging to the genus Madrepora, occupy a dominant position throughout this 

 reef-scape, and are represented by several distinct species. The little islet in the central foreground 

 comprises two varieties. The larger symmetrically ovate mass, Madrepora dccipiens, is, as it 

 grows, of a rich golden-brown hue, with whitish extremities. The smaller, irregularly-shaped 



