SALMONID^. 633 



waters indicated, even brackish water, and, in consequence, 

 we find a great variation of colour in one and the same species ; 

 others are more restricted in their hahitat, like S. solar, 

 S. ferox, etc., and, therefore, their coloration may be more 

 precisely defined. 



With regard to size the various species do not present an 

 equal amount of variation. Size appears 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 considerably in size, because they find the 

 same conditions in all the localities inhabited by them. A 

 widely spread species, however, like S.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 an abundance and variety of food, it attains to a 

 weight of fourteen or sixteen pounds. Such large Eiver-trout 

 are frequently named and described as Salmon-trout, Bull- 

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

 and tailed Batracheans, 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 stationary at a certain stage of development. 



The proportions of the various parts of the lody to one 

 another vary exceedingly in one and the same species. Be- 

 side the usual changes from the young to the sexually 

 mature form observed in all fishes, the snout undergoes an 

 extraordinary amount of alteration of shape. In the mature 

 male the intermaxillaries 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 entire head longer, than the 

 females ; with the intermaxillary bone the teeth, with which 

 it is armed, are also enlarged, sometimes to four times the 

 size of those of the females. And if this development of the 



