thp: appe.vuiculak .skeleton. 215 



the name time, now lies, as in the adult, almost parallel to the 

 backboDC ; 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 

 ulna, and the tibia and fibula, are at first independent of each 

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

 the two preaxial, I'adial or tibial , of each limb are established 

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

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

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

 not conclusive, is rather in favour of the view that it is the fifth, 

 and not, as is commonly held, the first digit or poUex that is 

 wanting. 



List of llin more important J'ublkaliuits dcuJi-iLg with the Di'velojrmenl 



of Froga. 



Alcock, T. : ' On the Development of the Common Fro;<.' Memoirs of tlie 



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

 Assheton, E. : ' The Development of the Optic Xerve of Vertebrates.' Quarterly 



Journal of Jlicroscopioal Science, vol. xxxiv. 1892. 

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

 Bambeke, C. van: ' Reoherches sur le D6veloppement du Pelobate brun.' 18G7. 

 ' Nouvelles liecherches sur I'Embryologie iles Batraciens.' Archives 



de Biologic, i. 1880. 

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



fiir mikroskopische Anatomie, xxix. 1887. 



' Die Riiokbildung des Frosohlarvenschwanzes und die sogenannten 



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

 Bedot, M. : ' Korherches sur le Dfiveloppement des Nerfs Spinaux ohez les 



Tritons.' .\rohives des Sciences I'hys. et Nnt., xi. 1881. 

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



bien.' Morphologisches Jahrbuch, vii. 1S81. 



' Beitrii^'e zur Angiologie der Amphibien.' Morphologisches Jahr- 

 buch, viii. 18K2. 

 Bourne, A. (j. : ' On Certain Abnormalities in tlic Common Frog.' Quarterly 



Journal of Microscopical Science, xxiv. 1884. 

 Cope, E. I). : 'On the Relations of the Ilyoid and Otic Elements of the Skeleton 



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

 Dug6s, A. : ' Rechcrches sur I'Osttologie et la Myologie des Batraciens 3, leurs 



difffirents Ages.' Mfimoiros de rAcadfimic des Sciences. Paris. 18.35. 

 Duval, M. : ' Sur le D6veloppement de I'Appareil Gi'nito-urinairedelaGrenouille.' 



llcvue des Sciences Naturellcs. 1882. 



