i8o THE COURTSHIP OF ANIMALS 



Crossbill. In this Salmon, too, the front teeth attain a 

 considerable length, while the body becomes laterally- 

 compressed and a hump forms at the shoulders. 

 Little, however, seems to be known as to the nature 

 of their battles. 



The combats of the Salmon of our own islands, how- 

 ever, are evidently severe, and this has long been known, 

 for Darwin speaks of as many as three hundred, all 

 with one exception males, being found dead in the Tyne 

 during the month of June, killed by fighting. Such battles 

 are fought, it is to be noticed, not so much for the pos- 

 session of females — for it is a polygamous fish — as for 

 the privilege of fertilizing the eggs as they are shed. 

 The absence of a " display " here is a noticeable feature, 

 and it is on this account, probably, that the reproductive 

 period is not associated with the appearance of any form 

 of resplendent livery. On the contrary, the marvellous 

 silvery sheen which adorned both sexes on their arrival 

 at the spawning ground from the sea has entirely vanished 

 by the time that the consummation of the journey has been 

 attained, and in its place is naught but a slimy, dingy 

 copper-coloured hue. But no sooner has the reproductive 

 period passed than the silver lustre makes its appearance 

 once more. 



These facts are the more interesting when contrasted 

 with what obtains among other fighting species which 

 must woo the females. Take the case of the common 

 freshwater Stickle-back. In this species the body is in- 

 vested with an armature of bony plates and spines in 

 place of scales, while the males are arrayed in vivid hues 

 of red and blue. Any survey, however, of the reproduc- 

 tive activities of this little fish must take into account 

 certain quite remarkable prenuptial actions and instincts. 



