56 The Natural History of the Salmon. 



to depend on the abundance of food and the extent 

 of the water. Thus the Salmon and the different kinds 

 of great Lake trout do not appear to vary consider- 

 ably in size, because they find the same conditions in 

 all the localities inhabited by them. A widely spread 

 species, however, like Salmo fario, when it inhabits 

 a small mountain pool, with scanty food, may never 

 exceed a weight of eight ounces, whilst in a large 

 lake or river, where it finds abundance and variety 

 of food, it attains to a weight of fourteen or sixteen 

 pounds. Such large River trout are frequently 

 named and described as Salmon trout, Bull trout, 

 etc. Further, in Salmones as in the majority of fishes 

 and tailed Batrachians, there is an innate diversity 

 of growth in individuals hatched from the same 

 spawn ; some grow rapidly and normally, others 

 more slowly, and some remain dwarfed and sta- 

 tionary at a certain stage of development. 



" The proportions of the various parts of the body 

 to one another vary exceedingly in one and the same 

 species. Besides the usual changes from the young 

 to the sexually mature form observed in all fishes, 

 the trout undergoes an extraordinary amount of 

 alteration of shape. In the mature males the inter- 

 maxillaries and the mandible are produced in 

 various degrees, and the latter is frequently more 

 or less bent upwards. Hence the males have the 

 snout much more pointed and produced, and the 



