INTRODUCTION. 85 



place has been selected and finished for the depo- 

 sition, or after they are hatched. There seems, 

 however, here also to be exceptions. " The Cal- 

 tichthys littoralis makes a regular nest of long 

 leaves, or grass, in which they lay their eggs in a 

 flattened cluster, and cover them over most care- 

 fully. They remain by the side of the nest till 

 the spawn is hatched, with as much solicitude as 

 a hen guards her eggs, both male and female, for 

 they are monogamous, steadily \vatching the 

 spawn, and courageously attacking any assailant. 

 Hence the negroes frequently take them by 

 putting their hands into the water, close to the 

 nest, on agitating which, the male springs furi- 

 ously at them, and is thus captured." * 



In their economical uses to man, fish are princi- 

 pally important as an article of food, and from 

 the employment they afford to the more depen- 

 dent classes ; but oil is the commodity greatest 

 in value and quantity produced from them. The 

 quantity of fish killed for these purposes is truly 

 immense. Fifty thousand salmon are said to 

 have been taken in the Tay during one year, 

 and five hundred thousand cod, on the New- 

 foundland bank, by a single vessel, in a week. 

 What then will be the aggregate of the ^sreatures 

 in this department of zoology which are yearly 



* Dr Hancock, Zoo/. Journ. XIV. p. 244. 



