72 THE STORY OF FISH LIFE. 



means an easy matter, and contains many pit- 

 falls and puzzles, for many cases appear to be 

 capable of bearing more than one interpretation. 

 Amongst the most interesting cases of this 

 kind are the instances where the male and 

 female are both brightly or even gaily coloured, 

 but in different ways. Thus in the ornate coffer- 

 fish (Ostradon ornatus) the male has a ground 

 colour of grass-green, with spots and stripes of 

 brilliant blue, whilst the female, often mistaken 

 for a different species, is pale yellow or flesh 

 colour with brown markings. In one of the 

 parrot fishes again we have a similar twofold 

 form, or case of dimorphism; the male being 

 green and red, and the female blue and yellow. 

 Usually, of course, where the sexes differ, the 

 male is brightly and the female dull coloured. 

 One instance, at least, is on record where the 

 markings of the young are more ornamental than 

 in the adult stages ; this is the case in the young 

 of certain eagle-rays of the genus Myliobatis. 



One of the most remarkable of all brilliantly 

 coloured fish is a small wrasse-like form, the 

 amphiprion. It is vividly coloured, being ver- 

 milion red banded with three cross-bands of 

 white. This seems about as conspicuous a coloura- 

 tion as possible, as if it had been adopted on this 

 account. At any rate, this fish plays the part of 

 a decoy for the mutual benefit of itself and a 

 gigantic sea anemone of some two feet in diameter, 

 which inhabits the coral reefs of Thursday Island. 

 It appears that this little monster resides within 

 the body of the anemone. When hungry he 

 emerges, swims about till he attracts the notice 



