Coloration of Murine Animals. 237 



or white. Some may cou.-iitl(M-, however, that such is a piovisioii 

 for rediicinp; the numb(M-3 of troublesome fishes. At any rate 

 the view that the pale under surface is protective meets 

 with exceptions in those forms. Again, the conspicuously 

 pigmented fins of the young mackerel midi^es {MoteWe) can 

 scarcely be for protection, unless they mimic spines when 

 collapsed, and the same may be said of the yellow pelvics of 

 the young ling. Mr. Beddard thinks the bright colour and 

 large size of the fins of certain fishes niay be jirotoctive (e. fj. 

 flying gurnard). Another example is the sapphirine gurnard, 

 yet in this case the protective function is doubtful. 



The transparent pelagic eggs of tiie cod tribe, flounder 

 tribe, and many others are supposed to escape notice by this 

 provision, but then the young becomes conspicuously tinted 

 before liatching, and therefore at a time when it is most 

 important that it should be invisible. If translucency be a 

 protection in the one case, colour under the same circum- 

 stances cannot likewise be so. 



The very great variety of markings and tints in larval 

 fishes under the same conditions shows tlie difficulty of 

 drawing rigid conclusions as to protective or warning colora- 

 tion in such forms, though they may be remnants of ancestral 

 coloration. Some might be disposed to think this a crucial 

 test of the theories propounded concerning the environment 

 of certain forms on land. Yet the history of the changes of 

 coloration undergone by a single species, e. g. the cod, shows 

 that important purposes are subserved by these changes. 

 Thus the minute larval cod escapes from the Qg\f with a series 

 of transverse bars ; then the black pigment is rearranged 

 longitudinally along the dorsum as it swims high in tiie 

 water. To this is by-and-by added yellow pigment, causing 

 (with the black) a greenish hue. When it seeks the rocky 

 margins it becomes boldly tessellated. At a later stage it 

 again becomes more uniformly tinted as it seeks the offshore, 

 though some whicli haunt the tangle-forests are boldly 

 blotched with reddish brown. In its adult state its sides and 

 dorsum are mottled with yellowisli green, though this does 

 not seriously affect its uniformity. If we attempt to contrast 

 the foregoing changes with those of the haddock, uncertainties 

 arise. The larval haddock has no transverse bars, though 

 bred side by side with the cod, but the dorsal band of black 

 pigment is developed in the next stage (post-larval). Instead 

 of seeking the shore the little hadilock keeps to deep water, 

 and it soon develops tho characteristic bold touches of black 

 on the sides above the pectoial region, the rest being uniformly 



Ann. ct- Mag. S. /li/if. Scr. 7. Vol. vii. 17 



