BRITISH FRESH-WATER FISHES 



dorsal. The tail bears the caudal fin. On the lower 

 part of the body there is the pectoral fin behind the hind 

 portion of the gill-covers, the ventral fin is right at the 

 base of the belly, and the anal fin is situate where the 

 body perceptibly narrow's towards the tail. The position 

 of these fins varies in certain kinds of fishes, and this will 

 be referred to when we are considering our own fresh- 

 water species individually, but it wdll be as well to set 

 out the uses of the fins just described. I have not read 

 a better account of these than appears in one of Mr. W. 

 J. Gordon's useful Handbooks, and I feel sure he will 

 allow me to repeat what he has written in his excellent 

 book " Our Country's Fishes." Mr. Gordon says : 

 " The caudal fin is the fish's main propeller, with the 

 paired fins he retains his trim, and the dorsal and anal 

 he uses as a keel to keep him straight on his course. 

 With his tail he does most of his steering, but he brings 

 in his pectorals to help him. A stroke of the tail to 

 starboard and a stroke or two with the starboard pectoral, 

 with the port pectoral held against the body, sends his 

 head to port ; a stroke of the tail to port with a stroke 

 or two of the port pectoral, and the starboard pectoral 

 held in, sends him round to starboard ; in fact the 

 pectoral thrown out of action serves as a pivot on which 

 he turns. Cut off a pectoral and he falls on the opposite 

 side ; cut off both and his head sinks ; cut off all his 

 fins and he capsizes, owing to his upper half being the 

 heavier." 



Some fishes have the eyes to the left, others to the right. 

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