Anatomy. — "0?i the development of the shoulder-ffir'dle and 

 eptsternnin in Reptiles". By Chh. van Gbi-dkrkn. (Coinninni- 

 cated bj Prof. L. Boi.k). 



(Communicated at the meeting of December 30, 1922). 



In comparaiive anatomy we distinguisli in tlie priinaiy shonlder- 

 girdle of most Sauria the scapula and siipiascapnla, ooi'acoid, epi- 

 coracoid and |)iocnracoid. Frocoiacoid and ooracoid are usually 

 liomologised with the similarly-named portions of the shoulder- 

 girdle of the Urodela and Annra. This was long ago contested by 

 GöTTE 'j. According to him there is nothing in the ontogenesis to 

 justify such an independence being attributed to the so-called pro- 

 coracoid of the Saiiria, for he holds that all ihe parts of the ven- 

 tral portion of the primary shoulder-girdle (in Cnemidophorus) 

 develop from one massive formation. The procoracoid of the Sauria, 

 therefore, he says, will not originate as a free cranio-ventral process 

 of the coracoid, to unite with it ventro-medially into a ring, as 

 GoTTE found it in Anura, and as in comperative anatomy it is 

 frequently termed with respect to the Sauria. Although such a 

 development was observed at a later date by Wikdehsheim '), BroOiM ") 

 and BociOLJUBSKi ') in a few other Sauria also, no hand-or text-books 

 (with the exception of that by Wiedersheim) make any reference to 

 this. It is this which has led to the present article, treating of the 

 development of the primary as well as the secondary shoidder- 

 girdle (including episternum). 



In intimate connection with the question as to the ontogenesis of the 

 episternum is another, namely, tliat of the development of the clavicula. 

 And attention will also be devoted to this in the following lines. 



The episternum, for the first data of the development of which 

 we have to thank Rathke '), was seen by the latter to originate 



>) A. GöTTE, Archiv. f. mikrosk. Anat. Bd. XIV, 1877. 

 -) R. Wiedersheim, Das Gliedmaszenskelett der Wirbelthiere. Jena, 1892. 

 ■t) R. Broom, Trans. South. Afric. Philos. See. Vol. XVi, Pt. 4, 1906. 

 *) S. BoGOUUBSKi, Zeitschr. f. Wissensch. Zool. Bd. 110, 19U. 

 ') H. Rathke, Ueber den Bau und die Entwickl. des Bruslbeines der Saurier. 

 Königsberg 1853. 



