SEXUAL SELECTION 435 



change, as Mr. J. K. Lord' believes, is permanent, and best 

 marked in the older males •which have previously ascended 

 the rivers. In these old males the jaw becomes developed 

 into an immense hook-like projection, and the teeth grow 

 into regular fangs, often more than half an inch in length. 



FiQ. 28.— Head of female salmon. 



With the European salmon, according to Mr. Lloyd,' the 

 temporary hook -like structure serves to strengthen and pro- 

 ject the jaws, when one male charges another with wonder- 

 ful violence; but the greatly developed teeth of the male 

 American salmon may be compared with the tusks of many 



* "The Naturalist in Vancouver's Island," vol. i., 1866, p. 54. 

 » "Scandinavian Adventures," vol 1., 1854, pp. 100, 104. 



