246 



TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY 



In the anterior part of the skull in Lates, Luciolates and other percomorphs the top view 

 (Figs. 117, 118) reveals a system of interlocking wedges and abutments. Thus the vomer 

 abuts against the mesethmoid, the latter is wedged in between the anterior limbs of the 

 frontal, they in turn are wedged in between the prominent lateral ethmoids. This system 

 of interlocking wedges, which extends also to the occipital region, is well seen also in the 

 top view (Fig. 294^) of Pomatomus. 



Thus in both isospondyl (Fig. 32) and percomorph (Fig. 117) the upper part of the 

 otic region has to bear the load of thrusts from the general forward movements of the body, 



pf&pareth ft 



..epiof 



P. arenatus 



Fig. 120 



Priacanthus 



Priacanthus. 



from the powerful jaw muscles (which rest directly and indirectly on the hyomandibular), 

 from the branchial arches, from the opercular apparatus and from the pectoral girdle. The 

 suspension of the latter by the forked posttemporal is well shown in Figure \\9A. As 

 Ridewood (1904a, p. 65) has pointed out, the inner fork of the posttemporal represents an 

 intermuscular tendon bone of the obliquely-placed neck muscles. 



With regard to the subdivision of the order Percomorphi into suborders and divisions, 

 Tate Regan (1913a, p. Ill) writes as follows: 



"At present I am inclined to recognize thirteen suborders, viz., Percoidea, Trichiuroi- 

 dea, Scombroidea, Siganoidea, Teuthidoidea, Kurtoidea, Gobioidea, Blennioidea, Stro- 

 mateoidea, Anabantoidea, Mugiloidea, Polynemoidea. But it is largely a matter of opinion 

 whether some of these may not be regarded as ordinally distinct, or whether others should 

 not rank merely as divisions of the Percoidea." 



He then subdivides the suborder Percoidea into twelve divisions each of which is care- 

 fully defined by more or less conspicuous characters. While for the purposes of the present 

 paper it has not been deemed necessary to follow this arrangement very closely, I have de- 

 rived much help from it in considering the relationships of the skull-forms described below. 



