FISHES OF THE EAST COAST OF NORTH AMERICA. 6 



of determining others. And as these questions involve several of the 

 species most important in an economical point of view, and as their de- 

 termination may farther throw much light on their geographical distri- 

 bution and their consequent relations to each other, physiological as 

 well as anatomical, their solution will be no slight boon to science. 



CLASSIFICATION. 



The classification adopted is that proposed by the author in his "Ar- 

 rangement of the Families of Fishes," (1872,) published by the Smith- 

 sonian Institution, and differs in many respects from that employed in 

 the "Catalogue of the Fishes of the Eastern Coast of North America," 

 (1861.) While, however, it is believed to be a much better exponent of 

 the real relations of the various forms, it is far from perfect, and little 

 attempt has been made to exhibit the forms in a natural sequence ; but, 

 to some extent, the task has been attempted. It is necessary to add, in 

 further explanation, that the series is an inverted ascending one, (and not 

 a true descending one); — that is, commencing with the most generalized 

 (or lowest) form, the various types have been successively approximated 

 in accordance with their affinities (or supposed affinities) to the preced- 

 ing forms; but, inasmuch as almost universal usage has accustomed the 

 ichthyologist to look for the specialized (or highest) forms first, they 

 have been so exhibited in the catalogue, subject to the modifications the 

 mode of procedure adopted entails. 



NUMBER OF SPECIES. 



It will be perceived that only about 351 nominal species are enumer- 

 ated in the present catalogue, while 394 were given in the catalogue 

 published in 1861, and yet about 50 species have been added since 

 that time. The diminished number is the result of reduction and ref- 

 erence of many nominal species to their proper types, and it is due to 

 the author to state that the necessity for most of those changes was 

 foreseen by him,* and that they were either first effected or the correct- 

 ness thereof first demonstrated by himself in various articles published 

 from time to time in scientific journals. The limit of reduction, so far 

 as respects species represented on the coast, has now been nearly (but 

 not quite) reached; but the ultimate reductions, already hinted at, will 

 doubtless affect, to some inconsiderable extent, the sum-total of the 

 number of fishes by the reduction of nominal American species to forms 

 of those previously described from elsewhere. 



FAUNAS.. 



The geographical ranges of the marine species of animals might be 

 best indicated by the names of the faunal regions admitted for the sev- 



" The number of species described iu the catalogue [of 18G1] nominally amounts to 

 394. It is probable that when the species are thoroughly investigated, the number 

 will be considerably reduced, and that many now retained with hesitation as distinct 

 will be identified with previously known ones."— (Gill, op.cit., 1861, p. 28.) 



