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Chap. XII.
Fishes.
333
Salmo lycaodon of N.-W. America the change, as Mr. J. K. Lord[1] 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
Fig. 27. Head of male common salmon (Salmo salar) during the breeding-season.
[This drawing, as well as all the others in the present chapter, have been executed by the well-known artist, Mr. G. Ford, from specimens in the British Museum, under the kind superintendence of Dr. Günther.]
the teeth grow into regular fangs, often more than half an inch in length. With the European salmon, according to Mr. Lloyd,[2] the temporary hook-like structure serves to strengthen and