84 INTRODUCTION. 



the millions of ova which are deposited, those 

 hatched to maturity will not exceed one in the 

 thousand, perhaps a much less proportion, and in 

 their great fertility we see both a beneficent de- 

 sign in furnishing an ample supply of food for 

 many of the inhabitants of the same element, and 

 for the numerous tribes of waterfowl which, at 

 some seasons, feed entirely on the eggs and fry ; 

 while, on the other hand, without this abundant 

 power of generation, a stock could not be saved 

 from the numerous enemies of sea and air to which 

 they are nearly constantly exposed. In general, 

 the eggs are deposited in water comparatively 

 shallow, upon rocks, on gravelly or sandy banks, on 

 aquatic plants, or marine algae, or in holes formed 

 in the banks or borders of the lakes or rivers ; 

 and to the strong instinctive principle which 

 impells these creatures to seek suitable situations 

 for the deposition of their spawn, do we owe the 

 abundant supply of fish which annually resort 

 to our shores. The migration of the herring, 

 mackerel, pilchard, &e. all depend on this, and 

 the countless shoals which arrive, only leave the 

 great recesses of the deep to seek the shallower 

 bays and estuaries for the purpose of continuing 

 their species. 



There is one circumstance in the breeding of 

 fishes which requires notice that of no care 

 being bestowed on the ova, or young, after a 



