air. 



FIG. 100. Formation of the amnion in the i-abbit. (After van Beneden, from 

 Jenkinson's Vertebral Embryology, Oxford, at the Clarendon Press.) 



h.am, Head amnion fold ; (.am, tail aninion fold ; <% embryo ; all, allantois : n.tr. 

 allantoidean trophoblast ; y.s, yolk-sac ; o.ti\ omphaloidean trophoblast : 

 i.-, extra-embryonic ca-lom : x.t, sinus terminalis of area vasculosa. 



FIG. 101. Fcetal membiant-s of horst-, lain >ta^<-. (After iH 

 Jenkinson's \'ertt'hrat>' Knibryulugi/, Oxfoixl, at the Clarendon 

 /. Villus : <<i>.th, epithelial thickenings of amnion : />, hipi>om:mi-s 

 amniotic cavitv : "//, allantois : //..<. volk-sjic. 



