142 THE NATURALIST IN AUSTRALIA. 



matic zoologists with whom small or fragmentary specimens alone have been hitherto 

 available for classificatory purposes. In recognition of the multitudinous growth-forms 

 exhibited by this particular coral, it is proposed here to provisionally distinguish it by 

 the suggestive title of Madrepora protceiformis. 



Many of the areas of the Abrolhos reefs were characterised by an interblending 

 of all of the various species of Madrepone enumerated in the foregoing paragraphs. 

 The author's attention was, however, particularly impressed by the very definite 

 border-like plan of their growth upon each side of the numerous river-like channels 

 which circulate through the Pelsart Island Lagoon. In the regularity of their 

 development and blended tints they vied, on colossal lines, with the artificially laid out 

 flower-parterres of a well-appointed garden. 



The endeavour has been made by the author in Chromo-Plate IV., facing 

 page 144, to commit to paper a faint and necessarily very inadequate idea of the 

 unique and remarkably beautiful spectacle yielded by an area occupied chiefly by the 

 violet-tinted Madrepora, as seen and roughly sketched while standing in the bows of a 

 small row boat, and drifting down one of the intersecting channels. Through the 

 glass-clear water in the immediate foreground every coral branch was distinctly visible, 

 the clustered coralla in many instances constituting harbours of refuge to parrot and 

 other fishes of the most brilliant hues, which would dart to and fro across the inter- 

 vening spaces as the boat approached. 



The horizon line, looking oceanwards, as shown in this sketch, was, in its way, 

 almost equally remarkable. The boundary in this direction is represented by the levelly 

 raised surface of the rocky platform, which constitutes a massive breakwater between 

 the placid waters of the lagoon and the tumultuous billows, which break unceasingly, 

 and with a sustained roar mightier than that of Niagara, upon the precipitous edge 

 of the outer barrier. An attempt has been made to portray the singular appear- 

 ance of the rebounding columns of water thrown up against the horizon - line 

 by the breaking waves, the altitude of which is optically greatly enhanced 

 by mirage. This atmospheric phenomenon is here, as throughout tropical seas, of 

 general occurrence. As an illustration of its prevalence, the very low points 

 of the archipelago of islands that enter into the composition of the Houtman's 

 Abrolhos commonly appear to be elevated to an abnormal height above the horizon. 

 A little further north, on the adjacent Western Australian coast, it is by no means 

 unusual, as the effect of mirage, for the passenger steamers to discover the boats of 

 the pearling fleets, or it may be of other denominations, some hours before they are 



