Fig. 361 — Continued 

 bony stapedial portion which articulates with the fenestra vestibuli and a distal carti- 

 laginous extrastapedial segment which connects with the external tympanic membrane. 

 The eustachian tube connects with the same tube on the contralateral side to form a 

 common opening into the dorsal pharyngeal area. The external ear opening is protected 

 by feathers. The ear of lizards resembles that of the bird, a short external auditory 

 meatus being present, protected externally in many instances by scales. In the frog, Rana 

 cavitympanum of Siam, the tympanic membrane similarly has moved inward and an 

 external auditory meatus is present. (M) The right membranous labyrinth of the shark, 

 Squalus acanthias. (Redrawn from Adams and Eddy, 1949, Comparative Anatomy, New 

 York, Wiley & Sons. (N) The right membranous labyrinth of the frog, Runa. (O) 

 The right membranous labyrinth of the pigeon, Columha. 



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