X THE COLOURS OF FISHES 211 



with spots and stripes of brilliant blue, while the 

 female, often classed as a separate species under the 

 name of O. aurita, is of a pale yellow or flesh-colour, 

 with brown markings; a so-called hermaphrodite 

 specimen was obtained by Mr. Saville Kent in 

 which the two sides displayed respectively the two 

 types of coloration. One of the parrot - fishes 

 also, Pseudoscarus rivulatus, displays marked sexual 

 coloration, the female being blue and yellow and the 

 male green and red, the prevailing tints during life 

 being respectively blue and green — an interesting 

 case because it recalls the conditions seen in some 

 parrots. In connection with the coloration of the 

 parrot- fishes there has been noticed a case of so- 

 called " mimetic " resemblance in the case of a goby 

 {Gobius douglasi), which is green banded with red, 

 the usual colours of the parrot- fish. The giant 

 anemones already mentioned have frequently small 

 commensal fishes living in their central cavities ; thus 

 Discosoma kenti is inhabited by Amphiprion percula, 

 a small red fish with broad white bands, the bands 

 being separated from the red ground colour by a 

 black margin ; Discosoma haddoni, on the other 

 hand, is inhabited by Amphiprion bicinctus, which is 

 closely similar in colouring but is without the black 

 margins to the white bands. Both sea -anemones 

 show great colour variation, but in all cases their 

 colours are sharply contrasted with those of their 

 commensals. 



It is interesting to note that the brilliancy of tint 

 is entirely confined to the fishes which actually live 

 among the brightly coloured corals. Those living 

 in the lagoons which are floored with coral sand and 



