166 



THE EVOLUTION OF MAN. 



deciduous membrane; these parts may be called the outer, 

 the inner, and the placental deciduous membrane. The 

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

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

 which coats the internal surface of the uterus wherever the 



FIG. 200. Human embryo, twelve weeks old, with its coverings ; natural 

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

 c, chorion; d, placenta; d', remains of tufts on Ihe smooth chorion ; /, <k- 

 cidua rejlcxa (inner) ; g, decidua vera (outer). (After Bernhard Schultze.) 



latter is not attached to the placenta. The placental in- 

 spongy deciduous membrane (d. placentalis or serotina, 

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



