25â 



K. MITSUKURI. 



Woodcut I. 



Invagination Cavity ( Archente ron) 

 Yolk-Plng 



Head-fold 



X 



Diagram of a Chelonian Egg. 



A — B represents the embryonic shield with the enclosed primi- 

 tive knob. Within the shield is established the whole of the future 

 embryo. A—X—B is the yolk-bag with the large subgerminal cavity 

 filled with nutritive liquid. The invagination -cavity which has ex- 

 tended forwards pari passu with the anterior extension of the primitive 



