62 Pub. Puget Sound Biol. Sta. Vol. 2, No 34 



PLATE 16 



For abbreviations see table of cell lineage. 



Fig. 18. Similar stage as Fig. 17 seen from the top. 



Fig. 19. Twenty-four cells completed. 



Fig. 20. Resting stage following the second division of the first 

 quartet; 28 cells. 



