Figs. 310-315. Skulls of fishes, to illustrate the mode of articulation of jaws and 

 branchial arches. 310. Skull of Scyllium. (After MARSHALL and HURST.) 311. Hep- 

 tanchus (Notidanus). (After HUXLEY.) 312. Chim&ra. 9 313. Ceratodus. (Slightly modi- 

 fied after HUXLEY.) 314. Polypterus. 315. Salmon. (After PARKER.) 



A. Articular. AG. Angular. BR. Branchiostegal rays. CHY. Ceratohyal. D. 

 Dentary. EHY. Epihyal. EPH, LG. Epihyal ligament. EPO. Epiotic. F. Frontal. 

 GHY. Glossohyal. HHY. Hypohyal. HM. Hyomandibular. IO. Interoperculum. 

 J. Jugal. LC. Labial cartilages. MCK. Meckel's cartilage. MPT. Metapterygoid. 

 MSPT. Mesopterygoid. MX. Maxillary. N. Nasal. NC. Nasal capsule. O. Opercu- 

 lum. OC. Opercular cartilage. OR. Suborbital ring. P. Parietal. PAL. Palatine. 

 PMX. Premaxillary. PO. Preoperculum. PTO. Pterotic. PTQ. Palatoquadrate. 

 PTY. Palatopterygoid. Q. Quadrate. SQC. Supraoccipital. SE. Supra-ethmoid. SM. 

 Symplectic. SO. Supraorbital. SP. Splenial. UMC. Upper median cartilage (not 

 frontal spine of male). 



Figs. 310, 314, 315 are regarded by HUXLEY as "hyostylic" (i.e. the hyoid element, 

 HM, attached by ligaments to the jaw hinge, taking an important part in the suspension 

 of the jaw; 311, a modified hyostylic condition ; the hinder upper margin of PTQ becom- 

 ing greatly enlarged, and attached by ligaments to the skull, is spoken of as "amphistylic " ; 

 312-313, were " autostylic," i.e. the upper jaw element fused with the skull. 



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