no. 3647 PERCIFORM FISHES — GOSLINE 5 



less real structural coherence. This basic structure is accepted here, 

 and such changes in subordinal status as are suggested have been 

 made with the idea of strengthening rather than altering it. A brief 

 account of the basis of perciform classification may help to explain this. 



The basal percoid fishes represent the greatest focal point of fish 

 evolution that exists today. Some 50 families of these with thousands 

 of species generally are recognized, and they dominate all of the 

 richer marine fish faunas. The families are differentiated on relatively 

 slight bases but to require any other would result in one tremendous, 

 taxanomically meaningless, and unmanageable family. As it is, the 

 Serranidae (sensu lato) has been tending in that direction (Gosline, 

 1966a). 



It is assumed that from the basal percoids an adaptive radiation 

 has taken place. Some of the lines of development have differentiated 

 very little, in which case they are still included with the basic stock; 

 others, considered separate superfamilies, somewhat more; separate 

 suborders, more still; and derivative orders, most of all. The 

 question which fish belongs in which taxon and why constitutes the 

 subject of perciform classification. Some of the theoretical and prac- 

 tical problems will be discussed briefly here. 



The basic difficulty is the old one of vertical vs. horizontal classi- 

 fications. Stated briefly: if, in figure la, the lineages, represented by 



Figure 1. — Diagrammatic representation of perciform radiation: a, hypothetical (see p. 6 

 for lettering); b, with actual suborders included. (At right of broken line in b are those 

 forms with dorsal and anal soft rays showing exact 1:1 correspondence with vertebrae; 

 to left of dotted line forms have about 2+ dorsal and anal rays per vertebra; between 

 dotted and broken lines normal ratio of 1 + ray per vertebra is maintained.) 



