4G8 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



forms. The student who will critically examine that mon- 

 ograph, however, will be dissatisfied on account of the insuf- 

 ficiency of characters, or the vagueness of others alleged to 

 differentiate the several forms, and the scepticism evoked 

 thereby would appear to be well justified by the examina- 

 tion of the fish themselves. Messrs. Gill and Jordan have 

 lately investigated the subject, and have come to the conclu- 

 sion that the species had been unduly multiplied, and that 

 the 43 species acknowledged by Suckley should be reduced 

 to 18. The total number of recognizable species of Salmones 

 now known from all the waters of North America is appar- 

 ently not more than 24. These 24 represent several well- 

 marked genera; which are primarily distinguished by osteo- 

 logical characters and the dentition of the vomer, but with 

 such characters are co-ordinated physiological and color pe- 

 culiarities which enable them to be recognized independent- 

 ly, and even render them convenient in practical use. The 

 importance of the group, and the universal favor with which 

 the species are regarded, justify a somewhat detailed enu- 

 meration here. 



Physiologically, the Salmones may be divided into two 

 categories: (1) those that pass all their lives in fresh water; 

 and (2) those whose lives are chiefly spent in the sea, but 

 which ascend fresh-water streams to multiply their race. 

 The former may indeed occasionally descend to the sea and 

 even flourish there, as in the case of the common trout of the 

 Eastern States, but their natural home is the fresh water, and 

 there they feed and increase ; the latter, of course, pass the 

 early portion of their lives in the fresh waters where they 

 were hatched, but at an early age descend into the sea, and 

 there remain and grow until the sexual instinct impels them 

 to ascend the streams. The fresh-water species undergo 

 comparatively little change during the breeding season ; but 

 in the anadromous representatives of the group, the males 

 develop more or less hooked jaws, assume hectic colors, and 

 die after their sexual duties have been performed. It seems 

 most probable that the salmon type was originally a fresh- 

 water form, and that the proneness to take to the salt w r ater 

 lias been a subsequently developed tendency. But, although 

 the anadromous habit and persistence in fresh water has been 

 found to be co-ordinated with structural characters, such is 



