GREGORY: FISH SKULLS 



263 



premaxilla is expanded, while that of the maxilla is narrow and rod-like —the reverse of 

 the usual relations of these elements. 



r 



Chiasmodon 



Fig. 137. Chiasmodon. 



In the skull of Mugil (Fig. 138) the marked antero-posterior expansion of the opercular 

 _..d the elongation of the pterotic and posttemporal may be conditioned by the enlargement 

 of the pharyngeal apparatus, but I do not understand the reason for the backward pro- 



ptm 

 h^om. spc 

 sphof pa • 



pfjpare+h tr 



an 



epiot 



cH 



Mugil cephalus 



Fig. 138. A/uji7 cephalus. 



