TII£: SKULL. 491 



form, in tlie higher types. They are more developed in the Cyclostomata 

 than in any other Vertebrate type. 



The meaning of these cartilages is very obscure ; but, from their being in 

 part employed to support the lips and horny teeth of the Cyclostomata and 

 the Tadpole, I should be inclined to regard them as remnants of a primi- 

 tive skeleton supporting the suctorial mouth, with which, on the grounds 

 already stated (p. 263), I believe the ancestors of the present Vertebrata 

 to have been provided. 



Bibliography. 



(439) A. Duges. "Recherches sur I'Osteologie et la myologie des Batraciens 

 a leur differents ages." Paris, Mem. savans etrang. 1835, and An. ScL Nat. Vol. 

 I. 1834. 



(440) C. Gegenbaur. Untersuchungen z. vergleich. Anat. d. Wirhelthiere, in. 

 Heft. Das Kopfokelet d. Selachier. Leipzig, 1872. 



(441) Giinther. Beob. nb. die Entuoick. d. Geh'drorgavs. Leipzig, 1842. 



(442) O. Hertwig. " Ueb. d. Zahnsystem d. Ampbibien u. seine Bedeutung f. 

 d. Genese d. Skelets d. Mundbohle." Archiv f. mikr. Anat., Vol. xi. 1874, suppl. 



(443)^ T. H. Huxley, "On the theory of the vertebrate skull." Proc. Royal 



The Elements of Comparative Anatomy. London, 1869. 



"On the Malleus and Incus." Proc. Zool. Soc, 1860. 



"On Ceratodus Forsteri." Proc. Zool. Soc, 1876. 

 " The nature of the craniofacial apparatus of Petromyzon." 

 Jouni. of Anat. and Phys., Vol. x. 1876. 



(448) T.H.Huxley. The Anatomy of Vertebrated Animals. London, 1871. 



(449) W. K. Parker. "On the structure aud development of the skull of the 

 Common Fowl (Gallus Domesticus)." Phil. Trans., 1869. 



(450) W. K. Parker. " On the structure and development of the skull of the 

 Common Frog (Rana temporaria)." Phil. Trans., 1871. 



(451) W. K. Parker. "On the structure and development of the skull in the 

 Salmon (Salmo salar)." Bakerian Lecture, Phil. Trans., 1873. 



(452) W. K. Parker. "On the structure and development of the skull in the 

 Pig (Sus sciofa)." Phil. Trans., 1874. 



(4.53) W. K. Parker. "On the structure and development of the skull in the 

 Batrachia." Part 11. Phil. Trans., 1876. 



(454) W. K. Parker. "On the structure and develoijment of the skull in 

 the Urodelous Amphibia." Part in. Phil. Trans., 1877. 



{455) W. K. Parker. "On the structure and development of the skull in the 

 Common Snake (Tropidonotus natrix)." Phil. Tram., 1878. 



(4.i6) W. K. Parker. " On the structure aud development of the skull in Sharks 

 and Skates." Trans. Zoolog. Soc, 1878. Vol. x. pt. iv. 



(457) W. K. Parker. "On the structure and development of the skull in the 

 Lacertilia." Pt. i. Lacerta agilis, L. viridis and Zootoca vivipara. Phil. Tram., 1879. 



(458) W. K. Parker. "The development of the Green Turtle." The Zoology 

 of the Voyaije of H. M.S. ChaUenger. Vol. i. pt. v. 



(459) W. K. Parker. "The structure and development of the skull in the 

 Batrachia." Pt. iii. Phil. Trans., 1880. 



(460) W. K. Parker and G. T. Bettany. The Morphology of the Skull. London, 



(460*) H. Rathke. Enticick. d. Natter. Konigsberg, 1839. 



(461) C. B. Reichert. " Ueber die Visceralbogen d. Wirhelthiere." Miiller's 

 Archiv, 1837. 



(462) W. Salensky. " Beitrage z. Entwick. d. knorpeligen Gehorknochelchen. " 

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Vide also Kiilliker (No. 29S), especially for the human and mammalian skull; Gotte 

 (No. 296). 



