46 SCIENCE SKETCHES. 



Specific names, in giving to these animals a scientific 

 nomenclature. Since Steller's time, writers of all 

 degrees of incompetence, and writers with scanty 

 material or with no material at all, have done their 

 worst to confuse our knowledge of these salmon, 

 until it became evident that no exact knowledge of 

 any of the species remained. In the current sys- 

 tem of a few years ago, the breeding males of the 

 five species known to Steller constituted a separate 

 genus of many species {Oncor/iynchtis Suckley) ; the 

 females were placed in the genus Salmo, and the 

 young formed still other species of a third genus, 

 called FariOy supposed to be a genus of trout. 

 The young breeding males (^grilse) of one of the 

 species {Oncorhytichus nerka) made still a fourth 

 genus designated as Hypsifario. Not one of the 

 writers on these fishes of twenty-five years ago 

 knew a single species definitely, at sight, or used 

 knowingly in their descriptions a single character 

 by which species are really distinguished. Not less 

 than thirty-five nominal species of Oncorhynchus 

 have already been described from the North Pa- 

 cific, although, so far as is now known, only the 

 five originally noticed by Steller really exist. 

 The descriptive literature of the Pacific salmon 

 is among the very worst extant in science. This 

 is not, however, altogether the fault of the authors, 

 but it is in great part due to the extraordinary 

 variability in appearance of the different species of 

 salmon. These variations are, as will be seen, due 

 to several different causes, notably to differences 

 in surroundings, in sex, and in age, and in con- 

 ditions connected with the process of reproduction. 



