PLATE 5 



EXPLANATION OF FIGURES 



Showing advanced stages in the development of the external parts of the eye 

 of the sparrow. I, lower lid; n,. nictitating membrane; p, feather follicles; u, 

 lower lid. X 15. 



28 Embryo at the age of 11 days. 



29 Embr3'o at the age of 12 days. 



30 Embryo at the age of 13 days, approximately the age of hatching. The 

 margins of the lids show the convoluted appearance similar to that of the adult. 

 The developing feather follicles in this figure have been omitted. 



332 



