182 T. THOMSON FLYNN 



Fig. 19.- — -Placental area showing section through a giantl. Note dis- 

 appearance of gland epithelium, the enlargement of the glantl lumen at the 

 apex and the tendency to form lateral slits in the plasmodium. This 

 section shows well the intruding leucocytes of the large mononucleate 

 type. The plasmodiblast shows a particularly noteworthy giant cell, 

 pigment patches, and ingested material. 



Fig. 20. — Section of placental area towards the margin. Cytoblast is 

 intact. The nests are well filled with plasmodiblast nuclei. 



Fig. 21. — Section of placental area at the margin. For description see 

 text. 



Plate 11. 



Figs. 22-27, Perameles uunni, 6-6 mm. Fit;. 28, Perameles obesula, 



7 mm. Fig. 29, Perameles obesula, 6-1 mm. 



Fig. 22. — .Section showing structure of the bi laminar omphalopleure. 



Note the extreme vacuolation of the ectoderm cells. 



Fig. 23. — The yolk-sac circulation. For description see text. 



Fig. 24.- — Diagram showing the relation of the embryo to its membranes. 



Figs. 25, 26, and 27. — Pigment- bearuig cells : fig. 25 of the serosa, 

 fig. 26 from the connective tissue, and fig. 27 from the troi^hoblast. 



Fig. 28. — Section through the mouth of a gland. 



Fig. 29.^ — Shows the relation of a plasmodial proliferation to a group of 

 syncytial nuclei. 



