PLATE 3 



EXPLANATION OF FIGURES 



Very much enlarged camera-lucida drawings, showing the development of the 

 external parts of the English sparrow eye. e, ear pit; I, edge of lids; m, outline 

 of eye showing through the ectoderm; n, nictitating membrane. X 15. 



22 Head of embryo 7 days old. 



23 Head of embryo 7j days old. 



328 



