THE TROUT 63 



form of Sticklebacks and small Pike, that those 

 which do get through find plenty of room and 

 plenty of food. 



During growth the caudal fin changes in form 

 from emarginate to truncate, the snout gets longer 

 and more pointed, the eye relatively smaller, and the 

 mouth larger. Large males also differ from the 

 females in having a longer head, a more produced 

 snout, and stronger jaws, the lower one often up- 

 turned at the tip. Thus we see that in localities 

 where the Trout grow large we may meet with fish 

 not only bigger, but very different in appearance 

 from any to be seen in places where only small 

 Trout are to be found. The so-called Great Lake 

 Trout, which has been recognized as a distinct 

 species under the name Salnio ferox, is in no way 

 different from a large Brook Trout. 



The size of the maxillary bone has been said 

 to characterize some of the races of Trout when 

 specimens are compared with others of the same 

 size and sex from elsewhere. However, the 

 differences are so slight that it is difficult to 

 appreciate them, and they may well be due to the 

 rate of growth and the nature of the food. 



The Lochleven Trout is one which has been 

 characterized by the weakness of the maxillaries, 

 but I find them to be much as in Trout from 

 many other localities. Another feature said to be 

 distinctive of the Lochleven Trout is the large 

 number of the pyloric caeca ; these appendages vary 

 from forty-five to eighty-two in Trout from Loch- 

 leven, more than are usually found in specimens 

 from other British localities. However, Mr. G. Sim 

 counted from twenty-nine to sixty-nine in fifty-two 



