PHOTOTYPE PLATES NOS. MI. AND JPI/. 17 



picture margin tiie upper moiety of a corallum of Pocillopora diuniconiis. A second example of 

 this last-named species occupies the centre of the reef-mass, with above, and a little to the right of 

 it, a symmetrical colony-stock of the larger Brain-stone coral Syinpliyllia hemispherica. In the space 

 between the Millepora and the Maeandrina a somewhat broken-up coral of a Prionastrtea may be 

 observed, belonging to that species usually distinguished, in life, by the brilliant green of its 

 calicinal centres. Alcyonaria, and, as in one of the neighbouring Port Denison reefs previously 

 described, brown Algae, contribute to the surface garniture of this reef-scape. 



PLATE VIII. 



NO. l.-DOG REEF, PORT DENISON. 



This view, in association with the preceding and the subsequent pictures, belongs to the 

 Saddle-back Island series. Its most remarkable characteristic, the one, in fact, that has won 

 for it its distinctive title, is the remarkable resemblance that one of the included coral-stocks 

 bears to a swimming dog. The position of this singular freak of Nature scarcely requires 

 special indication, being so conspicuously visible in the guise of a white-bodied, black-nosed 

 bull-terrier, with half-closed eyes, and depressed, shortly-cropped ears, making its wa}' across 

 one of the intervening channels So forcible is this likeness that it has been commonly mis- 

 taken for the object named by those who have seen the photograph. An equally (if not more) 

 remarkable mimetic object-analogy will be found associated with the Skull Reef that forms the 

 subject of Plate XiV. The dog-shaped coral-growth in the present reef-view represents, actually, 

 a colony-stock of a Goniastraea, allied to G. cxiiitia, with its upper surface just awash at the 

 particular state of the tide when the photograph was taken. A second, large, irregularly- 

 shaped, high-and-dry corallum of this species forms a prominent object near the centre of 

 the picture on the outer edge of the reef A noteworthy peculiarity of this coral variety is 

 the fact that, after very short exposure to the atmosphere, on the fall of the tide, the polyps 

 recede so far into the substance of the corallum as to be not only invisible, but to leave its 

 surface pure white, or with only a slightly greenish tinge, as though completely dead and 

 bleached. When first observed by the author at Thursday Island, these white coralla were 

 supposed to be defunct ; but on their re-inspection the following day under a higher condition 

 of the tide the polyps were exserted, and in a vigorous state of vitality. 



A species of coral included in this reef-scape, that has not entered into the composition of 

 the views previously described, is the finely subdivided, spiked variety just raised above water a 

 little to the left of the foreground centre. This is a species of Seriatopora, S. clcgaiis, or S. hystrix, 

 remarkable in life for its exquisitely delicate tints, which in the example referred to were a 

 vivid rose-pink. Coloured figures of the corallum and polyps of this species are included in Plate 

 VII, of the chromo-lithographic illustrations. A fine (in life, purplish) corallum of Pocillopora 



D 



