Fig. 212. — Chelonian blastoderms illustrating the development of the amnion. 

 (A and C after Mitsukuri, 1891.) 



A, Clemmys; B, Ohelydra ; C, Ctemmys. a, amnion with neural rudiment seen indistinctly through 

 it ; a.e, edge of amniotic flap ; a.t, amniotic tunnel ; eg, cephalic groove ; /, inconstant fold which is 

 sometimes present; g.r, gastrular rim ; m.f, medullary fold ; p.a, proamnion with head of embryo show- 

 ing through it. 



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