31 



Onlv GöTTK saw ;iii Cnemidoplionis) llie epistenmm comnieiice 

 as oaudal process ot" the clavicle. Well then, the foregoing casuistic 

 demonstration sliows the genetic connection of the clavicula and 

 episteriiiim, even though this is not so simple in Laceria as was 

 described by Gotte for Cnemidophorns. Herewith a new point of 

 agreement with the episternum of the mammals has been found. 

 Further, we have seen that the e|)isternal halves lie at first quite 

 craniaily from the iialves of the breast-bone. Only later, with the 

 comineiiceuient of the longitudinal bar does a small portion of the 

 epislerinini of the Sauria couie to lie ventrally from the sternuui. 

 The (iitferent position of the episterniun thus seems to exist but 

 partially, and it occurs secoinlarily. The oidy difficulty in homolog- 

 izing the episterna of Reptilia and Mammalia is thus the histogenetic 

 difference. And GrAtPP^) has demonstrated that too much iuiportance 

 must not be attached to this in general. 



As for the clavicle, respecting tlie^development of which my resear- 

 ches couiirmed its primary connection with the scapulo-coiacoideum, 

 I do not deem it advisable for tiie present to enter into the discussion 

 which is being carried on as to its homology, although in the theory 

 developed bij Göthe (homology of the clavicle with the "Procoracoid" 

 of the Ani[ihibia, which he terms the clavicula; and of which 

 WiEUEKSHEtM, •') Oil the basis of his own investigations, proves himself 

 an advocate (in the last edition of his " Vergleichende Anatomie" 

 WiEDERSHEiM luis changed his 0[iiiiion. for wiiat reason I do not 

 know) there is midoiibtedly a certain attraction. 



SUiMMARY. 



1. Fenestrae in the shoulder-girdle of the Sauria develop secondar- 

 illy, in a girdle of the type of Sphenodon. 



2' The incisura scapulo-(pro)coracoidea is likewise a fenestra of 

 which the cranial border, except fuv some cartilaginous remains, is 

 reduced to a ligament. 



3. The clavicle originates as a blastematic process from the 

 scapulo-coracoideum. 



4. The episternum proceeds from a paired formation. This formation 

 is the product of the hoinolateral clavicular process. 



5. As long as there are no data of the development of the girdle 

 of Chelonia, (here is nothing which obliges us to assume a proco- 

 racoid in any reptile, homologous with that of the Amphibia. 



') E. Gaupp, Kopfskelett in Heetwig's Handbiicli. Jena, 1905. 



*J R. WiEDERSHEiM, Grundrisz d. Vergl. Anat. d. Wirbelthiere. 4e Aufl. Jena 1898. 



