PLATE 3 



EXPLANATION OF FIGURES 



69 Normal embryonic stages 24 to 35. 



24 Optic cups but no contact of medullary folds. 



25 Contact of medullary folds, but no proamniotic fold. 



26 Proamniotic fold, but no caudal amniotic fold. 



27 Caudal amniotic fold, but anterior neuropore and otocysts still open. 



28 Anterior neuropore and otocysts closed. Amniopore still open. 



29 Amniopore closed. Forelimb becomes a club. 



30 Forelimb paddle. Secondary lumbar flexure. 



31 Diameter of allantois approximately one-third length of body. Hind limb 

 bud. Frontal process. 



32 Diameter of allantois approximately two-thirds length of body. Hind 

 limb club. 



33 Diameter of allantois equal length of body. Hind limb paddle. Eyelid 

 folds. 



34 Oral shield. Epitrichium covers eyes, ears, and sides of mouth. Claws 

 on forelimb digits. 



35 Oral shield practically resorbed. Umbilical cord lost or very much 

 constricted. 



