226 EMBRYOLOGICAL TYPES 



as their predecessors, and when the adult feathers are properly 

 formed, the nestling-down is worn off. 



Literature 



Jenkinson, J. W. Vertebrate Embryology. Oxford, at the Clarendon 



Press, 1913. 

 Kellicott, W. E. Chordate Development. Henry Holt, New York, 



1913. 

 Lillie, F. R. The Development of the Chick. Henry Holt, New York, 



1919. 



