438 WILLIAM K. GREGORY 



English method of Dr. G. A„ Boulenger. 1 The discovery of the 

 reasons for this divergence in method, of the common grounds 

 upon which both systems rest, and of a means of harmonizing 

 these differences in a new or compromise classification, may be 

 facilitated by a glance at the recent history of the taxonomy of 

 fishes, and by a brief reference to some of the principal functions 

 of "natural" classifications in general. 



First, as to the history of systematic ichthyology. 



In England Giinther's 2 classification was long held as orthodox. 

 It represented more especially the combined labors of Cuvier, 

 J. Muller, Agassiz, and Gunther himself, and was essentially pre- 

 evolutionary in method. The larger groupings were fairly 

 natural, but many of the smaller ones were really heterogeneous, 

 and held together by homoplastic characters. The chief criteria 

 of classification were external characters. 



In America Cope and Gill approached the subject from the 

 standpoint of evolution. Cope 3 in 187 1 sketched out the broad 

 lines of a new classification based on a careful study of a large 

 osteological collection. This classification was founded to a large 

 extent upon internal, skeletal characters. As compared with 

 previous systems it was also founded on a larger number and range 

 of characters and was thus less subject to the deceptive effects 

 of characters resulting from convergent or parallel evolution. 



Gill 4 had already recognized the naturalness of the assem- 

 blages called by him Nematognathi, Eventognathi. In 1872 

 Gill published his "Arrangement of the Families of Fishes" 5 

 which was revised and extended in his memoir 6 of 1893. 



i-Teleostei (Systematic Part), The Cambridge Natural History, vol. 

 "Fishes, Ascidians," etc., 1904, pp. 539-727. 



2 An Introduction to the Study of Fishes, 8vo, Edinburgh, 1880, 

 pp. xii-xvi. 



3 " Observations on the Systematic Relations of the Fishes," Proc. 

 Amer. Assoc. Adv. Sci., 20th meeting, Indianapolis, 1871, pp. 317-343. 



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

 Proc. Acad. Nat. Sci., Phila., 1861, pp. 1-63. 



5 "Arrangement of the Families of Fishes, or Classes Pisces, Marsipo- 

 branchii, and Leptocardii," Smithsonian Misc. Coll., No. 247, 1872, pp. 

 i-xlvi, 1-49. 



6 "Families and Subfamilies of Fishes," Mem. Nat. Acad. Sci^ Vol. VI, 

 pp. 125-138. 



