PELVIC GIRDLE. 497 



(Gegenbaur, Parker) regarded as the prsecoracoid, but Gotte has pointed 

 out that in its mode of development it strongly resembles the clavicle of 

 the higher forms, and behaves quite differently to the so-called prsecoracoid 

 of Lizards. It is however to be noticed that it differs from the clavicle in 

 the fact that it is never segmented off from the coraco- scapular plate, a 

 condition which has its only parallel in the equally doubtful case of the 

 Chelonia. Parker holds that there is no clavicle present in the Amphibia, 

 while Gegenbaur maintains that an ossification which appears in many of 

 the Anura (though not in the Urodela) in the perichondrium on the 

 anterior border of the cartilaginous bar above mentioned is the repre- 

 sentative of the clavicle. Gotte's observations on the ossification of this 

 bone throw doubt upon this view of Gegenbaur ; while the fact that the 

 cartilaginous bar may be completely enclosed by the bone in qiiestion 

 renders Gegenbaur's view, that there is present both a clavicle and prse- 

 coracoid, highly improbable. 



No interclavicle is present in Urodela, but in this group and in a 

 number of the Anura, a process grows out from the end of each of the 

 bars (prsecoracoids) which Gotte holds to be the clavicles. The two pro- 

 cesses unite in the median line, and give rise in front to the anterior 

 unpaired element of the shoulder girdle (oinosternum of Parker). They 

 sometimes overlap the epicoracoids behind, and fusing with them bind 

 them together in the median line. Parker whe has described the paired 

 origin of the so-called omosternum, holds that it is not homologous with 

 the interclavicle, but compares it with his omosternum in Mammals. 



BIBLIOGRAPHY. 



(463) Brnch. "Ueber die Entwicklung cler Clavicula und die Farbe des Blutes." 

 Zeit.f. wiss. Zool., iv. 1853. 



(464) A. Dugs. " Eecherches sur 1'osteologie et la myologie des Batraciens a 

 leurs differens ages." Memoires des savants etrang. Academie royale des sciences de 

 Vinstitut de France, Vol. vi. 183.5. 



(465) C. Gegenbaur. Untersuehungen zur vergleichenden Anatomie der Wirbel- 

 thiere, 2 Heft. Schultergiirtel der Wirbeltliiere. Brmtftosse der Fische. Leipzig, 1865. 



(466) A. Gotte. "Beitrage z. vergleich. Morphol. d. Skeletsysteras d. Wirbel- 

 thiere : Brustbien u. Schultergiirtel, Archiv f. mikr. Anat. Vol. xiv. 1877. 



(467) C. K. Hoffmann. "Beitrage z. vergleichenden Anatomie d. Wirbelthiere." 

 Niederlandisches Archiv f. Zool., Vol. v. 1879. 



(468) W. K. Parker. "A Monograph on the Structure and Development of the 

 Shoulder-girdle and Sternum in the Vertebrata." Eay Society, 1868. 



(469) H. Rathke. Ueber die Entwicklung der Schihlkroten. Braunschweig, 1848. 



(470) H. Rathke. Ueber den Bau und die Entwicklung des Brustbeins der Saurier, 

 1853. 



(471) A. Sabatier. Comparaison des ceintures et des membres anterieurs et pos- 

 tenenrs d. la Serie d. Vertebres. Montpellier, 1880. 



(472) Georg 'Swirski. Uiitersuch. ilb. d. Entwiek. d. Schultergilrtels u. d. 

 Skelets d. Brustjlosse d. Hechts. Inaug. Diss, Dorpat, 1880. 



Pelvic girdle. 



Pisces. The pelvic girdle of Fishes is formed of a cartilaginous 

 band, to the outer and posterior side of which the basal element of 

 the pelvic fin is usually articulated. This articulation divides it 

 into a dorsal iliac, and ventral pubic section. The iliac section never 

 articulates with the vertebral column. 



In Elasmobranchii the two girdles unite ventrally, but the iliac 



B. E. II. 32 



