29 



portion of the episterimiii, a coiDinencement of bone appears. More- 

 over, a thill candallj-diiecied biastematic process has also appeared. 

 Finally iiluslration (/ shows the state of the epistermim just before 

 the right and left parts blend to one nnjiaired episternnm. One 

 blastema tlins gives liae to one clavicnla -j- tiie half of the episternum, 

 augmented in- the inembrana episterno-clavicnlaris lying between 

 them, which is nothing else than the reduced centrnin of the original 

 honiogeneons blastema and by the lig. episteriio-claviculare, that 

 lies in the lateral border of the membrane of the same name. 



If we now consider that of this joint process only tiiat portion 

 exists (irst from which tiie clavicula develops, I believe 1 may conclude 

 that the episternnm is pairedly formed from the clavicular processes. 

 This manner of growth would ini|>ly that without the clavicle there 

 would be no episternum, a stale of matters as is seen in Rhipto- 

 glossa. The conditions as found in adult crocodiles (an episternnm 

 but no clavicula) is explained by Wiedkrsheim's discovery, namely 

 that embryos of crocodilns contain a rndimeniary clavicula. Of the 

 peculiar manner of ossiticalion of the clavicula, as described by 

 GöTTK and others, 1 coulil not find any trace. 



We have still to see what compai'ative anatomical conclusions 

 may be di'awn from the above. 



In the large comprehensive works upon comparative anatomy the 

 opinion formulated by Gegenbaur is expressed i.e. a great independence 

 is ascribed to the cranial boundary of the fenestra principalis. This 

 boundary, the pro('oracf)id, is said to be the homologue of the 

 similarly-named slionlder-giriUe part of the Anura, Urodela and 

 Chelonia. The jirocoracoid would thus occur in two main types, 

 viz. as cranio-ventral process of the coracoideuni in Urodela and 

 Chelonia, and as cranial border of a fenestra in Anura and Saiiria. 

 Sphenodon has no procoracoid. The publications of Göttk, Wiedekshkim, 

 Broom and Bogoejubski have not been able to bring about anj' 

 change in this theory. Now the coracoideum (in a wider sense) of 

 the Sauria occurs in very ditferent forms viz. 1*' entirely without 

 fenestras in Sphenodon and Chamaeleo; 2'"^ with one fenestra, 

 which has been named fenestra principalis on account of its frequent 

 occurrence (Fürbbingbr; "Hauptfenster" Gegenbaur); 3"' with, 

 besides the fenestra principalis, one or two more "Nebenfenster". 

 The latter are said to have no morphological value, wherea.'^ the 

 ,, Hauptfenster" has. Now we know from Gotte that in Cnemido- 

 phorus spec. (3"' group: one principal and two minor fenestrae) ail 

 the fenestrae develop secondarily by regression of parts of the 

 shoulder-girdle, or in other words, that the early-embryonal Saurian- 



