46 SALMONIDJ;. 



" In the markings they are so distinct as to be at once 

 separated from the Trout by any observer. The row of blue 

 marks which is also found in the young Trout, and in the 

 young of several Salmonida, in the Parr are narrower and 

 more lengthened. The general spotting seldom extends 

 below the lateral line, and two dark spots on the gill-cover 

 are a very constant mark. On a still closer comparison 

 between the young Trout and Parr of similar size, the 

 following distinctions present themselves : The Parr is alto- 

 gether more delicately formed ; the nose is blunter, the tail 

 more forked ; but the chief external distinction is in the 

 immense comparative power of the pectoral fin : it is larger, 

 much more muscular, and nearly one-third broader ; and we 

 at once see the necessity for this greater power, when we 

 consider that they serve to assist in almost constantly sus- 

 pending this little fish in the most rapid streams. Scales 

 of the Parr taken from the lateral line below the dorsal fin 

 were altogether larger, the length greater by nearly one- 

 third, the furrowing more delicate, and the form of the canal 

 not so apparent or so strongly marked towards the basal end 

 of the scale. The greater delicacy of the bones in the Parr 

 is still kept up very distinctly. The operculum forming 

 the posterior edge of the gill- cover is much more rounded 

 than in the Trout, approaching in this respect to the Sal- 

 mon ; in the Trout the lower part is decidedly angular. 

 The interoperculum in the Parr is longer and narrower. 

 The maxillary bone is broader at the posterior corner, but 

 much shorter in the Parr ; the vomer is much weaker ; the 

 bones or rays of the gill-covers are longer and much nar- 

 rower than those of the Trout. The teeth of the Parr are 

 smaller ; the bone of the tongue longer, weaker, and not so 

 broad; the under jaw much weaker, and the distance be- 

 tween the two sides of the under jaw in the Parr about one- 



