THE APPENDICULAR SKELETON. 215 



the same time, now lies, as in the- adult, almost parallel to the 

 backbone ; and the hip joint is shifted to the extreme hinder 

 end of the body. 



c. The limbs. The skeletal framework of each limb develops 

 from the proximal towards the distal end ; the humerus and the 

 femur being the first bones to be differentiated. The radius and 

 La. and the tibia and fibula, are at first independent of each 

 Ler, but the cartilages of each pair soon fuse. Of the digits, 

 two preaxial, radial or tibial, of each limb are established 

 it ; the others budding out in succession. There is some 

 lubt as to which of the normal five digits is absent in the 

 id of the adult frog ; and the embryological evidence, though 

 >t conclusive, is rather in favour of the view that it is the fifth, 

 not, as is commonly held, the first digit or pollex that is 

 i,ntin g. 



it of the more important Publications dealing with the Development 



of Frogs. 



cock, T. : 'On the Development of the Common Frog.' Memoirs of the 



Manchester Literary and Philosophical Society, series hi., vol. viii. 1883. 



Assheton, R. : ' The Development of the Optic Nerve of Vertebrates.' Quarterly 



Journal of Microscopical Science, vol. xxxiv. 1892. 

 Balfour, F. M. : 'A Treatise on Comparative Embryology,' vol. ii. 1881. 

 Bambeke, C. van: ' Recherches sur le Developpement du Pelobate brun.' 18(>7. 

 ' Nouvelles Recherches sur l'Embryologie des Batraciens.' Archives 

 de Biologie, i. 1880. 

 Barfurth, D. : ' Versuche iiber die Verwandlung der Froschlarven.' Archiv 

 fur mikroskopische Anatomie, xxix. 1887. 



• Die Ruckbildung cles Froschlarvenschwanzes und die sogenannten 

 Sarkoplasten.' Archiv fiir mikroskopische Anatomie, xxix. 1887. 

 Bedot, M. : ' Recherches sur le Developpement des Nerfs Spinaux chez les 



Tritons.' Archives des Sciences Phys. et Nat., xi. 1881. 

 Boas, J. E. V. : ' Ueber den Conus arteriosus und die Arterienbogen der Ampbi 

 bien.' Morphologisches Jahrbuch, vii. 1881. 



' Be it rage zur Angiologie der Amphibien.' Morphologisches Jahr- 

 buch, viii. 1882. 

 Bourne, A. Gr. : 'On Certain Abnormalities in the Common Frog.' Quarterly 



I Journal of Microscopical Science, xxiv. 1884. 

 ?e, E. D. : ' On the Relations of the Ilyoid and Otic Elements of the Skeleton 

 in the Batrachia.' Journal of Morphology, ii. 1888. 

 ges, A. : ' Recherches sur l'Osteologie et la Myologie des Batraciens a leurs 

 difterents Ages.' Memoires de l'Academie des Sciences. Paris. 1835. 

 val, M. : 'Sur le Developpement del'AppareilGenito-urinairede la Grenouille.' 



