GREGORY: FISH SKULLS 



247 



The otoliths of the Perciformes, as described by Frost {1927b) afford valuable hints as 

 to the inter-relationships of some of the families of this enormous assemblage. The sagitta 

 of Perca fluviatilis, which is regarded by Frost as the type, is ovate with concave outer and 

 concave inner side. A related type is found in the otoliths of Serranus from the Upper 

 Eocene of the Isle of Wight (Frost, 1925c, p. 160). 



Basses, Perches, Groupers. The family Serranidae, the central group of the Per- 

 coidea, is the subject of a beautifully illustrated work by Boulenger (1895). Morpho- 



epiot 

 .'pfo 

 ' (St) 



Hagmulon 



Fig. 121. Hamulon sp. 



logical variability of the skull characters within the family seems slight but there are marked 

 diflFerences in the proportional measurements, the skull being markedly elongate and low in 

 Luciolates, short and deep in Casioperca lepidoptera (p. 311). 



The cranium of the marine Australian apogonid fish Dinolestes (Fig. 140C) as described 

 and figured by Starks (1899a) presents considerable resemblance to that of Luciolates. 

 Starks was able to confirm Gill's conclusion that this fish has nothing to do either with 

 Esox or with Sphyrana, but that it is a true percoid of the family Apogonidae (Cheilodip- 

 teridae). 



Priacanthus. — The most striking feature of this skull (Fig. 120) is the huge size of the 

 orbit and the anteroposterior crowding of the opercular. The mouth, although fairly short, 

 can open upward because the quadrate-articular joint is brought forward to near the an- 

 terior border of the eye and because the quadrate is lowered. 



