CORALS AND CORAL-ANIMALS. 145 



no means insignificant size. A photographic illustration of this species, in addition to the coloured 

 lithograph, is given in Plate XXI. of the photo-mezzotype series, in association with the 

 description of which plate further details concerning this handsome species are recorded. As 

 therein stated, the species being undoubtedly new to science, the author has conferred upon it 

 the title of Discosonia HaMoiii. In common with the preceding type, this fine Discosoma occurs 

 abundantl}' among the reefs of the Great Barrier system, from Torres Strait southwards to Macka}'. 



A phenomenon of high interest is associated with the two giant anemones just described. 

 Both of them, in point of fact, act the part of hosts to other living organisms of appreciable size ; 

 the guests comprising two species of fish, and also a species of prawn. The larger species, 

 Discosoma Kcnfi, almost invariably contains two or more specimens of a percoid fish about 

 three inches long, that is identical with the Aiiipliiprioii pciriila of Lacepede. On thrusting a stick 

 into the oral orifice of the anemone the fish swim out, but return immediately to their residence 

 within the gastric cavity of their host on the removal of the disturbing missile. The fish thus 

 furnished with free lodgings by the anemone is notable for its brilliant coloration. The ground 

 colour in this type is a bright orange-vermilion, interrupted by three pearly-white cross-bands, 

 which, as well as the edges of the fins, are bordered with black. A coloured representation of this 

 species, characteristically illustrating the conspicuous colour contrast it makes with its adopted 

 host, is included in Chromo plate No. I. The second species of fish, AiiipIiiprioii biciiuius, that 

 similarly lodges with Discosoma Haddoni, but dines out, presents the same orange-vermilion ground 

 colour, but possesses onlj' two white cross-bands, and neither these nor the fins are edged with 

 black. It is similarly illustrated in Chromo plate No. II. in close contiguity with its Actinarian 

 host. In a third species of this genus, apparently identical with Amphiprion melanopiis, collected 

 by the author at Port Darwin, there is only one intersecting band of white, and as this crosses 

 the fish's head and cheeks it communicates to it the ludicrous appearance of having its face 

 bandaged as though for toothache. At first sight it was, as a matter of fact, imagined that a 

 scrap of white paper was accidentally adhering to the fish, and it was only on attempting to 

 remove it that it was recognised as forming an integral part of the organism. 



An additional guest entertained by the bead-tentacled Discosoma Haddoni is a species of prawn 

 about two inches long, apparently referable to the genus Palaemon, and also illustrated in Chromo 

 plate No. II. It is remarkable that the dominant tints of this crustacean coincide with those 

 of the fish Amphiprion, being white and red, although in this instance the darker colour is in 

 abeyance. These corresponding, very conspicuous, colours in the separate commensal guests of 

 the sea-anemones doubtless fulfil some important function in the vital economy of the associated 

 organisms. What that function is it is difficult to tell ; but, by way of a tentative guess, it might 

 be suggested that the brilliant colours of the commensal guests attract the notice of other predatory 

 fish, which, hastening to seize an apparently easy prey, are themselves entrapped within the 

 outspread tentacles of the passively expectant sea-anemones. Their function under such conditions 



