PLATE 3 



EXPLANATION OP FIGURES 



5 Mouse girdle. Scapulae, coracoids, clavicles, and presternum, all in one 

 continuous mesenchymatous girdle, which is similar to that of the dogfish (fig. 1) 

 and the marsupial fetus (fig. 35). From the Washington University School of 

 Medicine Embryological Collection, series no. 102, slide 4, section 16. 



6 Human embryo girdle. Mesenchymatous stage. First appearance of 

 clavicle; presternum and coracoids present. From The Johns Hopkins Em- 

 bryological Collection, series no. 424, slide 5, section 16. 



CI, clavicle PSt, presternum 



Cr, coracoid Sc, scapula 



96 



