303 



skeletal bone. The significance of this foramen is unknown as 3et. 



As to the ossificalioM of tlie scapula ray experience proved it not 

 to he so simple as is represented in the literature. 



The earliest ossitication I observed in an embryo of •40 mm. I 

 constructed a wax model (fig-. 4) of the scapula of this embi'yo. 



-CUa 



Fig. 4. 



Fig. 5. Homo 40 mm. Transversal. 

 Cor = Processus coracoideus; B.U = Humerus; 

 ^cr = Processus acroniialis; Sc = Scapula. 



Like the preceding model this also is viewed from above and 

 from tiie dorso-iatei'al side. What this reconstructed model shows 

 us may follow here: 



The joint-cavity, lying at the level of the first rib, is now 

 located almost entirely on the planum scapulae (as with the adult 

 scapula). Of the S|)ina not a trace is visible as yet, the margo supe- 

 rior is not thickened. To the basis of the processus acromialis an 

 area of closely packed mesenchyma is attached, which extends 

 between the muscular tissue and separates the rudiment of Muse. 

 supra-, and infraspinatus. 



This area of mesenchyma is cut in a cross section as represented 

 in fig. 5. Behind the root of the processus acromialis begins a peri- 

 chondrial ossification, which continues into this condensed mesen- 

 chyma. This ossification is the first formation of the spina. We see, 



