21 



III tlie vential medial line (he clavicular-blastema of both sides are 

 still distinctly separated. 



Those parts of' the coracoid which were still blastemalic in the 

 former embi'vos have decreased in density and have become some- 

 what lighter, (fenestra principalis and raembr. scapnio-procoracoideal. 

 The later lig. scapnlo-procoracoideum has remained praechondral. 

 Pro- and epicoracoid now consist of cartilage. Fig. 3 shows four 

 sections taken fiom this series (not consecutive). Section a contains 

 the procoracoid, the lig. scapnlo-procoracoideum and the scapula; 

 section h has already passed (more caudalh') through the later 

 membrana scapulo-procoracoidea ; section c contains also the thinner 

 blastenm wiiicli cories|)onds to the later fenestra principalis; section 

 (/ tinallv conlains (inly coracoideum s. sir. (and scapula). 



^caj> 



Fig. 3. Lacerta agilis L. Gross-section. 



Embryo Lacerta ag. N. (N.T. about 32). The entire detiiiite 

 coracoid in a wider sense is now present in cartilage. In the bridging 

 over of the incisura scapulo-procoracoidea, the praechondrium has 

 diminished while the blastema has increased. The thinning of the 

 blastema corresponding to the membrana scapulo-procoracoidea and 

 to the fenestra principalis, already seen in the preceding embryo, is 

 continued here. The definite form of incisura and fenestra is clearly 

 recognisable. 



In the blastema which joins the clavicula caudally a still slight 

 ceutiul thinning can be seen. Simultaneously, in the unthiuited. 



