478 CHORDATA. 
Fig. 329.—DIAGRAMS OF THE Fa:raL MEMBRANES OF A 
MAMMAL. 
Epiblastic Disc, 
ae 
clase ras 
Hypoblastic Disc. 
Epiblast. Extra- 
<i _Hypoblast. f embryonic. 
Fluid in Yolk-sac. 
A, The diploblastic embryo of a mammal in section. 
Amniotic 
Folds. | Epiblast of Embryo. 
aivi y Hypoblast of Embryo. 
'Villi of Serosa, 
Fluid in Yolk-sac. 
B, A later stage with serosa villi and a developing amnion, 
