GREGORY: FISH SKULLS 



167 



MORMYROIDEA 



In the third superfamily, Mormyroidea, specialization and instability in certain 

 features finally result in bizarre forms of body and skull. 



Hyodon. — As described by Ridewood (1904c, pp. 206-210), the least aberrant is the 

 genus Hyodon of North America, which retains fairly normal toothed jaws and body form. 



sym 



Hyodon alosoides 



Fig. 60. Hyodon alosoides. After Ridewood. 



The most conspicuous specialization of the rather short skull (Fig. 60) is the relatively 

 prominent dentition on the narrow parasphenoid, which is bowed downward far below its 

 normal level, perhaps in order to bring its teeth near to those on the tongue and floor of 



