The mackerel is the head, or typical fish, but one of the 

 smallest in size, of a large family, which has representatives 

 in every sea in the world, except in the regions of extreme 

 cold, and every member of which is excellent as food. 



The first distinguishing mark of the family to an outside 

 observer is a tail having a peculiar fork. You can see it in 

 a moment in the fish market here. The next is the 

 cleanness of the lines on which the fish is built. The long 

 conical forepart of the body and snout, the smooth round 

 body, and the clean run of the afterpart, all fit the fish for 

 rapid propulsion through the water, whilst the powerful 

 forked tail, working with much less opposition to the water 

 than would a rounded tail, and precisely with the action 

 with which the sailor sculls his boat by one oar over the 

 stern, enables the fish to make the greatest possible use of 

 the advantages of its shape. The last distinguishing exterior 

 feature which I shall notice is the existence between the 

 base of the tail fin, and the hindmost upper and under fins, 

 and both above and below the body, of a series of little 

 soft rudimentary fins, called finlets, and the use of which is 

 obscure. This family includes the bonitos, the tunnies, the 

 albacores, and other Mediterranean fish, all occasional 

 visitants of our Western seas, and just excludes (if, indeed, 

 it does exclude, for I, who have seen the fish, am not clear 

 about it,) the Northern " opah," a noble great fellow, some 

 four to five feet long, which would more than cover an 

 ordinary card -table, and is a very Assyrian for "gleaming 

 in purple and gold," being in fact almost the only northern 

 fish which excels in splendour of colour the fish of the seas 

 of the temperate zones and the tropics. I do not at this 

 moment recollect whether there is a specimen of this fish 

 in the building. If there is, you will find it in the court of 

 Norway or possibly of Denmark. 



