THE SKELETAL SYSTEM 

 X 



221 



Fig. 179. — Dorsal and ventral views of the skull of turtle, Trionyx. ho, basioccipital; 

 bs, basisphenoid; eo, cs, exoccipital; /, frontal; j. zygomatic (jugal); m, mx, maxilla; «, 

 prefrontal; opis, opisthotic; p, (behind orbit) postfrontal, (others) parietal; pal, palatine; 

 pmx, premaxilla; pno, prootic; pt, pterygoid; q, quadrate; s, supraoccipital; v, vomer. 

 (From Kingsley's "Comparative Anatomy of Vertebrates.") 



SUPRAOCCIPITAH 

 BASlOCCIPITAl; 

 HYOMANDIBULARn 

 SQUAMOSALS^ 

 PAR I ETAL- 

 PARASPHENOID^ 



1ST VERTEBRA 



NEURAL SPINE 



PTERYGOIDS^, 

 FRONTAL^~^_; 



ECTETHMOID^^O'^^'' 

 MESETHMOID 

 NASAL- 

 PALATINE 



-OPERCU.AR 

 — y-^ — PREOPERCULAR 

 ■^^^^SUBOPERCULAR 

 ■SYMPLECTIC 



QUADRATE 

 /2_.|MTER0PERCULAR 



Fig. 180. — Skull of hake in left lateral aspect. Membrane bones are cross-hatched, 

 pro-cartilage bones stippled. Compared with the skull of ganoids, that of teleosts 

 shows an increasing dominance of membrane bones over those preformed in cartilage. 



