84 DEVELOPMENT OF THE SKELETON OP THE TUATARA. 



PLATE V. 



SpIIENODON PUNCTATUS. — THE QUADRATE, IITOID, AND COLUMELLA AURIS. 



an., angular; b., boundary between stajies and extrastapedial cartilage; h.a., branchial arch ; 

 h.c, branchial cleft ; cJ", horizontal semicircular canal ; ca., carotid artery ; ca.', branch of carotid 

 artery; c.nu., auditory capsule ; c.c, extrastapedial cartilage; ew., eustachian recess ; /e.^ fenestra 

 in siiprastapedial cartilage; /«.', anterior cornu of the hyoid;/v., jugular vein; mk., Meckel's 

 cartilage; mt., mouth; n. v.-xi., cranial nerves; n.viiJ, branch of chorda tympani ; ph., pharynx; 

 p.p., parotic process; pq., pterygoquadrate ; rj., quadrate; cj.', otic process of quadrate; s.a., supra- 

 angular ; srjj, anterior process of squamosal ; sg.", posterior process of squamosal ; s..^t., supra- 

 stapcdial cartilage ; si., columella (stapes) ; stJ, boundary between columella and extrastapedial 

 cartilage. 



Staye P. A series of sections, in order from within outwards, showing the primary 

 relationships of the columella auris to the hyoid and quadrate. x 40. 



Represents the most internal section No. 1. 

 Represents section No. 6. 

 „ No. 8. 

 „ No. 19. 

 „ No. 27. 

 Stage Q. A similar series to the above. X 25. 



Represents the most internal section No. 1. 

 Repi'esents section No. 11. 

 „ No. 26. 

 „ No. 36. 

 „ No. 46. 

 „ „ No. 57. 



Fig. 12. Stage R. Transverse section of auditory region passing through quadrate and columella 



auris. x 25. 



Figs. 13-14. Stage S. Sections, in the same order as figs. 1-5, showing the relation of the 



suprastapedial cartilage to the quadrate. x 20. 



Fig. 13. Represents the more internal section No. 1. 



Fig. 14. Represents section No. 16. 



Figs. 1-5. 



Sta_ 



Fig. 



1. 



Fig. 



2. 



Fig. 



3. 



rig- 



4. 



Fig. 



5. 



Fig. 6-11. 



Stc 



Fig. 



6. 



Fig. 



7. 



Fig. 



8. 



Fig. 



9. 



Fig. 



10. 



Fig. 



11. 



