78 FISHES. 



towards the Teleosteous type, tlie number of separable bones 



Pmx 



I 



j»mx 



Fig. 39.— Skull of Polypterus. (After Traquair.) 

 Fig. I. Upper aspect of the Primordial Cranium, with the membrane-bones 

 removed. Fig. II. Lower aspect of the same. Fig. III. Side view, with the 

 membrane-bones. Fig. IV. Lower aspect of the Skull, part of the bones 

 being removed on one side. The parts shaded with oblique lines are cartilage 

 of the primordial skull. 

 An, Angular ; ao, anteorbital ; Ar, articulary ; B, basal ; D, dentary ; E, 



