HEAD-MUSCLES IN GALLUS AND OTHER SAUEOPSIDA. 531 



separation from it (Chelone), becomes a part of the skull, 

 and tlie quadrate becomes immovably fixed. 



In Sphenodon tlie upper part of tlie myotome is at first an 

 elevator of the pterygoid process (text-fig. 24, p. 528) ; it sub- 

 sequently loses this function on fixation of the pterygo-quad- 

 rate, and ties its pterygoid and epipterygoid processes to the 

 side of the skull, with an insertion of a very few of its lowest 



sphen pterQuad 



ffon hyCi' 

 ofTiohyoid 

 ant my/o 



Text-fig. 28. — Transverse section through an embryo of Sphe- 

 nodon, in "stage E. " of Howes and Swinnerton. (For explana- 

 tion of lettering see p. 555.) 



fibres into the fixed palato-pterygoid bar (text-figs. 28 and 

 29, pp. 531, 532) — forming the spheno-pterygo-quadratus of 

 Fiirbringer. 



In Agama the upper part of the myotome, after a temporary 

 insertion into the pterygoid process (text-fig. 30, p. 534), 

 becomes inserted into the pterygoid bone forming the pterygo- 

 parietalis and protractor pterygoidei^ muscles. In some 



' Of Versluys. 



