Pig. 100. — Formation of the amnion in the rabbit. (After van Beneden, from 

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



h.am. Head amnion fold ; t.am, tail amnion fold ; e, embryo ; all, allantois ; a.tr, 

 allantoidean trophoblast ; y.s, yolk-sac ; ^ o.tr, omphaloidean trophoblast ; 

 c, extra-embryonic coelom ; s.t, sinus terminalis of area vasculosa. 



Fig. 101. — Foetal membranes of horse, later stage. (After Bonnet, from 

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



■V, Villus ; ep.th, epithelial thickenings of amnion ; A, hippomaiies ; am.r, 

 amniotic cavity ; all, allantois ; y.s, yolk-sac. 



