10 



HUMAN EMBRYOLOGY AND MORPHOLOGY. 



cartilage (palato-quadrate). In fishes the Palato-auadrate bar 

 forms part of the mandibular arch (Fig. 10 A). In mammals the 

 quadrate is completely separated from the pterygoid and, instead 



Meckels cartilage 



a. 



quadrato-jugale 

 quadrate (1)-^ 



os articulare (4) 



palate (3) 

 maxilla 



premaxilla 



Mechels cartilage 



11. 



palato-quadrate bar 

 fncus (quadrate) 



,Eus. cart. 



ilate 



-internal pterygoid 



■ int. lot. lig. 



tympamc (quad.-jug.)'~y^y/ T^S^a-^- ^xr obliterated 



malleus (os articulare) Mechels cartilage 



symphysis 



Fig. 10, a, b, c. — Showing what become of the skeletons of the Mandibular Arch 

 (Meckel's Cartilage) and Maxillary Process (Palato-quadrate Cartilage). The 

 numerals indicate corresponding parts. 



A. In Fishes and Amphibians. B. In Reptiles and Birds. C. In Mammals. 



of acting as a supporting bone for the lower jaw, as in birds 

 is subservient to hearing, and known as the incus. 



It is difficult to understand, as Dr. Hans Gadow has pointec 

 out, how a bone such as the quadrate, constantly engaged witl 



