6 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 124 



the radiating lines, are traced back to their bases, in this case into 

 the basal mass of percoid families, then how does one distinguish 

 them? Contrariwise, if a line XY, representing some theoretical stage 

 of structural development, is drawn across the radiating lines and 

 everything below XY is called a suborder Percoidei, then how does 

 one classify the parts of the radiating lines above XY? 



Omitting from present consideration the mugiloids and anabantoids, 

 Regan (1913), followed herein, places all of the Perciformes below a 

 theoretical line XYin the suborder Percoidei. Matsubara (1955, 1963), 

 following the lead of Jordan and others, adopts what is probably a 

 more consistent approach and divides the areas both above and below 

 XY into separate divisions; e.g., the Percina, Chaetodontina, Caran- 

 gina. As far as I can determine, there are no concrete morphological 

 criteria for the separation of the more basal groups, and a decision as 

 to which of the basal percoid families should be assigned to which 

 section has to be made on a largely intuitive or authoritarian basis. 

 Furthermore, I feel no intuitive assurance that such a group as the 

 Chaetodontina is not an assemblage of similar-looking but unrelated 

 fishes. It may well be that when other and sharper tools are devised 

 for investigating the relationships of percoid families (see, e.g., Frei- 

 hofer, 1963) elimination of the line XY and the basal suborder Per- 

 coidei will prove feasible. For the moment, however, recognition of a 

 central group Percoidei seems preferable. 



Such a recognition, as already noted, causes difficulties in the 

 treatment of the percoid-derivative taxa. If all of the radiating lines 

 below XY (for example c, d, and e) are considered to belong to the 

 single suborder Percoidei, then should all the individual lines above 

 XY, however close (for example a and b), be considered separate 

 suborders? Regan (1929; seems to have adopted essentially this 

 course in recognizing the Siganoidea (Teuthidoidea) as distinct from 

 the related Acanthuroidea, the Scombroidea distinct from the Tri- 

 chiuroidea, etc. In this, I do not follow him. In the first place, 1 can 

 see no compelling logic in the procedure. In the second, it has the 

 practical result of creating a tremendous basal suborder Percoidei 

 with numerous splinter offshoot suborders. Here, the concept of a 

 derivative percoid suborder is that it should contain fishes more 

 closely related to one another than to any other fishes outside the 

 boundary of the suborder Percoidei. This concept admits the possi- 

 bility that a derivative suborder may have been polyphyletic at the 

 time it crossed the fine XY. In practice (fig. 16) it has the effect of 

 combining certain of Regan's (1929) suborders. 



Another problem of perciform classification is that of determining 

 which lineages should be recognized as derivative suborders rather 

 than as full orders. Many factors have a bearing on this question. 



