94 



LILLIE. 



EXPLANATION OF PLATE III. 



Fig. 28. Twenty-two-cell stage from the upper pole ; rolled somewhat to the 

 left. 



Fig. 29. The same egg from the left side. Larval mesoblast — Y — partly 

 overgrown by jr2 and ds {cf. PI. II, Fig. 25). 



Fig. 30. Slightly later stage from the upper pole. Second division of </« . 

 Fig. 31. Formation of j; 3 . Upper pole. 



Fig. 32. Same egg. Lower pole. Formation of third generation of ecto- 

 meres. 



Fig. 33. Upper pole. Formation of jc 3 . 



Fig. 34. Lower pole. Formation of third generation of ectomeres. 

 Figs. 35-38. Four views of the same egg after the formation of x3 and the 

 third generation of ectomeres. Twenty-seven-cell stage. 

 Fig. 35. Upper pole. 



Fig. 36. Anterior view; in part from above. 

 Fig. 37. Direct view from in front. 

 Fig. 38. Lower pole. 

 Fig. 39. The next stage from below. The indicated cleavage of D completes 

 the separation of the germinal layers, x^'xa. process of formation. 



