HOUTMAN'S ABROLHOS. 145 



has commenced to grow retrogressively from its broken end. The original 

 axial corallite has in this manner developed a shoot about three-quarters of an inch 

 long, from which numerous lateral corallites have also commenced to bud. 



Mention has been previously made of the close resemblance of this purple-tinted 

 Stag's-Horn Coral to the Madrepora hebes of the Queensland coast. As an illustration 

 of the correspondence that may be observed in their respective growth plans, 

 a photograph of a tidally exposed reef area, consisting almost exclusively of that 

 variety taken by the author in the vicinity of Lark Passage on the Great Barrier, 

 is reproduced on page 144. Additional reef views embodying the same type will be 

 found in the writer's volume especially descriptive of the Great Barrier Eeef products. 

 The coral on this Queensland reef lacked the brilliant tints of the Abrolhos colony- 

 stocks, being for the most part of a warm brown hue with whitish tips. Some few of 

 the coralla among the mass were, however, brilliant green or lilac, while in other 

 localities the same species was met with in which the greater portion of the coralla 

 was bright grass-green, but every branch tip to the extent of about half-an-inch, 

 an intense violet. As recorded by the writer in the volume above quoted, the colour 

 characters of the Madreporidse are not only exceedingly variable in the same species, 

 but are even unstable in individual coralla. Thus a colony-stock of the type under 

 notice, Madrepora helm, growing in a pool at Thursday Island, Torres Straits, 

 was, when first observed, made up of pinkish-brown stems and branches with 

 greenish-white tips, while the polypes were all of a light emerald-green tint. On examin- 

 ing the same growths two years later, it was observed that the branches and main 

 stems were now a dark seal-brown and their tips, to a large extent, a pale lilac-blue 

 tint, while the polypes had assumed, for the most part, a clear red-brown hue. It 

 is consequently quite possible that the reef areas in Pelsart Island Lagoon here 

 portrayed, may at some future date be found to have exchanged the purple tints 

 recorded in 1894 for more sombre brown or brilliant green. 



Next to Madrepora, the genus Montipora builds up the most conspicuous coral 

 developments in Pelsart Island Lagoon. Its members are chiefly of either an encrusting or 

 a foliaceous character, and in many instances of the most brilliant violet or even magenta 

 hue. Selected specimens, quickly dried in a breeze, still in the writer's possession, have 

 retained for over two years much of their pristine splendour, and exhibit sufficient of 

 their original tints to convey to the untravelled a faint idea of their living beauty. One 

 species of this genus Montipora, apparently new to science, but identical with a type 

 collected by the writer also at the Palm Islands on the Queensland coast was notable 



