GREGORY: FISH SKULLS 199 



"In the Ostariophysi the saccular otolith, the sagitta, which is generally the principal 

 otolith in other fishes, is attenuated and diminutive. In the Cyprinoids and Diplomysles 

 the asteriscus is the largest otolith, in the Siluroids (except Diplomystes and a few South 

 American species) the lapillus. It seems possible that the reduction of the sagitta may be 

 related to the development of the Weberian mechanism, and that the great development 

 of the lapillus or utricular otolith, in the Siluroids, may in muddy waters compensate for the 

 decreased use of the eyes for maintaining equilibrium." 



The otoliths also throw light on the interrelationships of the siluroid families with 

 each other and with the primitive characins (1925f, pp. 445-446). 



A utricular otolith resembling those of the siluroids has been recorded by Frost (1926a, 

 p. 83) from the Upper Jurassic of England. Here is another suggestion of the relative 

 antiquity of the ostariophysial fishes. 



