BIGELOW. Development of Lepas. 



PLATE 9. 



Figures from three sets of consecutive serial sections. Vegetative (ventral) pole 

 and blastopore are at the left in Figures 74-80 and at the lower side in Figures 

 81-86. Blastoderm one cell in thickness. 



Figs. 74-77. Series of consecutive sections parallel to sagittal plane from an egg 

 in sixty-two-cell stage, counting two dividing primary mesoblasts 

 as four cells. The first and sixth sections of this series contained 

 only blastoderm cells and have not been figured. 



Figs. 78-80. Series of consecutive sections parallel to sagittal plane through egg 

 in a stage with about one hundred and twenty cells. The first and 

 last sections of the series are not figured. 



Figs. 81-86. Series of consecutive transverse sections (viewed from their posterior 

 faces) from an egg in same stage as that of last series. Figure 81 

 shows the most posterior of the sections represented. The first and 

 last sections of the series, containing only blastoderm cells, and 

 three anterior to and similar to Figure 86 have not been figured. 



