1 66 



THE EVOLUTION OF MAN. 



deciduous membrane ; these parts may be called the outer, 

 the inner, a,nd the placental deciduous membrane. The 

 outer or true membrane {d. externa or vera, Fig. 198, dv, 

 Fig. 200, g), is that portion of the uterine mucous membrane 

 which coats the internal surface of the uterus wherever the 



Fig. 200. — Hninan embryo, twelTe weeks old,Tvitli its coverings; natural 

 size. The navel cord passes from the navel to the placenta : 6, amnion ; 

 c, chorion ; A, placenta ; d\ remains of tufts on the smooth chorion ; /, de- 

 cidua, refiexa (inner) ; g, decidua vera (outer). (After Bernhard Schnltze.) 



latter is not attached to the placenta. The placental or 

 spongy deciduous membrane (d. placentalis or serotina, 

 Fig. 198, plih, Fig. 200, d) is simply the maternal placenta 



