PLATE II 



Pygoscelis papua. 



Fig. I. Embryo, stage i8 (No. 3). a, sero-amniotic connective; 

 al, allantois; c, visceral clefts;/, fore-limb rudiment; h, hind-limb 

 rudiment; p, pericardiac wall; v, ventricle (of heart). 



Fig. 2. Embryo, stage 25 (No. 4). al, allantois; h, hind-limb bud; 

 hy, hyoid arch; m, mandibular ridge; mx, maxillary ridge ;3', yolk stalk. 



