340 FISHES 



male after deposition, and it is a most curious case of adaptation 

 of sexual instincts that the male is sexually excited, not by the 

 presence of the female of his own species, but by the sight of 

 the mussel in which the eggs have been deposited. 



The spawning habits of the salmon have been already 

 mentioned in connection with their migration. Other fishes, 

 that is the great majority of the species in the class, whether 

 they produce adhesive eggs like the perch and other fresh-water 

 fishes, and the herring, or transparent buoyant eggs like most 

 marine fishes, show no parental instincts but leave the eggs to 

 develop without protection. 



