THE SALMON FAMILY. 333 



fishing is useless ; but such a water when it is clearing, or 

 a full water that is not discoloured, is highly favourable. 



The two golden maxims for fly-fishing are, first, to keep 

 as far from the bank and as much out of sight as possible ; 

 and secondly, always to use finer tackle than any one else 

 on the river, and (your skill being equal) you will always 

 catch the most fish. As it has been cleverly parodied, 

 " Tell me what your tackle is, and I will tell you what 

 your basket is." 



Principal Characteristics of the Common Trout (Salmo fario). (Taken 

 from a Hampshire fish, 12 inches in length.) Length of head com- 

 pared to length of head and body, without tail-fin, as 1 to 4 ; depth 

 of body rather greater than length of head. Profile of back and belly 

 about equally convex. Head blunt; lower jaw longest when the 

 mouth is open, but shutting within the upper jaw on its being closed. 

 Back-fin commencing halfway between point of nose and commence- 

 ment of upper rays of tail-fin ; third ray of back-fin longest, and longer 

 than base of fin. Small back -fin commencing halfway between origin 

 of large back-fin and upper extremity of tail-fin ; pectoral fin two- 

 thirds of length of head ; ventral fins under middle of first back-fin, and 

 halfway between origin of pectoral fin and end of base of anal fin ; 

 anal fin beginning halfway between origin of ventral fin and com- 

 mencement of lower rays of tail-fin. Tail slightly forked, very gra- 

 dually becoming square, or slightly convex in very old fish (as shown 

 in figure, p. 320). Form of gill-cover, see figure at p. 30. Pyloric 

 caeca* seldom exceeding 46 in number. Teeth numerous, strong, and 

 curving inwards, in six rows on upper surface of mouth and jaw, and 

 four on lower. (See also p. 35; and for distinguishing features between 

 teeth of Common Trout and Sea-Trout, p. 309.) Teeth (as through- 

 out the Salmon and Trout family) larger in males than in females. 



* The pyloric caeca are narrow pouches or culs-de-sac, more or less 

 numerous, attached to the pylorus or mouth of the intestines. 



