84 COMPARATIVE ANATOMY. 



The lower jaw, each ramus of which is composed of a single 

 piece, corresponds to the anterior portion only (dentary, splenial, 

 and coronoid) of the mandible of Sauropsida, and it articulates 

 secondarily with the squamosal. Concerning the primary relations 

 of these parts, compare the chapter on the auditory organ and 

 Fig. 67. The hyoid arch is often reduced to a fibrous band, the 

 st} 7 lo-hyoid ligament, and is connected proximally with the base of 

 the auditory capsule and distally with the third visceral (that is, 

 the first true branchial) arch. The latter forms the proper body of 

 the hyoid with its greater cornua. Bemains of the fourth visceral 

 (second branchial) arch are present in some cases, as in the Porpoise 

 (Phocsena), for example. For the air-sinuses of the skull compare 

 the chapter on the air-sacs of Birds. 



BIBLIOGRAPHY. 



AHLBORN, F. Ueber die Segmentation des Wirbelthicrkorpers. Zcitschr. f. wiss. 



Zool. Bd. XL. 1884. 



CALLENDER, G. W. Formation, &c., Human Face. Phil. Trans. 1869. 

 DAMES, "W. Veb. den Bau des Kopfes von Archceopteryx. Sitz. d. k. preuss. Akad. 



d. Wiss. 37 and 38, 1882. 

 DOHRN, A. Studien zur Urgcschichte des Wirbelthierkorpers. Mittheilungen der 



Zoolog. Station zu Neapel. Bd. VI. 1885. 

 DURSY, E. Entw.-Gesch. des Kopfes des Menschen und der hoheren Wirbelthiere. 



Tubingen, 1869. 

 GEGENBAUR, C. Unters. z. vergl. Anatomic der Wirbcllhiere, H. III. Das 



Kopfskdet der Selachier. Leipzig, 1872. 

 HERTWIG, 0. Ueber das Zahnsystem der Amphibien und seine Bedeutung fur die 



Genese des Skelets der Mundhohle. Arch. f. mikr. Anat. Vol. XL Suppl. H. 



1874. 

 HOWES, G. B. On some Points in the Anatomy of the Porpoise. Journ. of Anat. and 



Physiol. Vol. XIX. 1879. 

 MARSH, 0. C. The Dinocerata, a Monograph of an Extinct Order of Gigantic 



Mammals. "Washington, 1884. 

 MOLDENHAUER, Die Entwick. d. mittleren u. des aiisseren Ohr. Morplwl. Jahrb. 



Bd. III. 1878. 



MULLER, J. Vergl. Anatomic der Myxinoiden. Berlin, 1834-1845. 

 PARKER, W. K. Numerous Papers on the Development of the Vertebrate Skull 



in the Transactions of the Royal, Zoological, and Linnean Societies for the last 



twenty years. 

 PARKER, W. K., and BETTANY, G. T. The Morphology of the Skull. London, 



1877. 

 STOHR, P. Zur Entwick. des Kopfskeletes der Teleostei. Festschrift z. Feier des 300 



Jdhrigen Bestetens der Jul. Max. Univ. zu IVurzburg. Leipzig, J882. Zur 



Entwick. des Urodelen- und Anurenschadels. Zcitschr. fur IViss. Zool. Bd. 33 



und 36. 

 WIEDERSHEIM, R. Salamandrina pzrspicillata, &c. Versuch einer vergl. Anatomie 



der Salamandrinen. Genua, 1875. Das Kopfskdet der Urodelen. Morplwl. 



Jahrb. Bd. III. 1877. Die Anatomie der Gymnophionen. Jena, 1879. 

 WYHE, J. W. VAN. Ueber die Mesodermsegmente und die Entwicklung der Nerven des 



Selachicrkopfes. Amsterdam, 1882. 



V. LIMBS. 



The limbs or extremities, which are, as appendicular organs, 

 distinguished from the axial organs (head, neck, and body), 

 serve mainly for locomotion, and may be divided into two groups, 



