1888.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 585 



exceptional range of variation among the mail-cheeked fishes can be 

 effectively presented to the general student of ichthyology. 



It may be asked, what is the reason for the great difference between 

 the system herein proposed for the mail-cheeked fishes and those fol- 

 lowed by previous writers? It is sufficient to reply that we have been 

 guided by a consideration of the entire structure and by the assump- 

 tion that the whole is greater than auy of its parts. In some, at least, 

 of the previous essays at subdivision and segregation of the group, the 

 principle that a part is greater than its whole, although of course not 

 avowed, has been practically carried out. In this connection we may 

 recall the principles of the father of natural history, which have too 

 often been disobeyed, and which deserve re-enforcement, even though 

 their formulator himself often sinned against them: 



Qua? in uno geuere ad genus stabilienduni valent, miuimo idem in altero necessario 

 pra>stan f . 



Scias characterem non constituere genus sed genus cliaiacterein ; characteremlluere 

 egenere, non genus e charactere ; ebaractererem non esse, ut genus fiat, sed ut genus 

 noscatur. (Linn., Phil. Bot., § 169.) 



COMPARISON. 



It is interesting and instructive to note the different manner in which 

 the group of mail-cheeked fishes has been treated by three prominent 

 investigators. 



Cuvier, the man of great genius and talents, amongst the scattered 

 masses of fishes which he was called upon to consider, noticed the 

 superficial resemblance between the various mail-cheeked fishes, and 

 his search for a common character was rewarded by the discovery of 

 the development of the enlarged elements of the suborbital chain, on 

 account of which he named the group designated by him as the family 

 of "mail-cheeked" fishes (Joues-cuirassees.) 



Giinther, a man meritorious for industry, but deficient in genius 

 and scientific tact, failed to appreciate a generalization already duly 

 formulated. Impressed by the most superficial characters, he ignored 

 the generalization of Cuvier, widely separated the constituents of the 

 group recognized by the great naturalist, and asso ciated the scattered 

 members with forms with which they have little or no relationship. This 

 divorce has been dissented from or protested against as unnatural by 

 almost all the French and Scandinavian as well as American ichthyol- 

 ogists. So poteut, however, has been the influence of a great w-ork — 

 great in the sense of voluminous and as the outcome of laborious indus- 

 try — that the most unnatural classification proposed by the anglicized 

 ichthyologist has been followed by almost all the English and German 

 naturalists. 



Kaup, the "nature-philosopher," applied fancy to his consideration of 

 the group, aud its results have already been exhibited. 



