I 



segmentation cavity f s.6 . ) is partially fil celis. 



tell 

 The 1 - ' to have been cut off from the cen- 



tral periblast f c ,p , ). from which it is y a cell 



so delicate t oil immersion only .'/ill detect it. 



It is lik - Last further in that its pe con- 



tains . ranules; 



i. I., is an arched type, writ L hest 



point rather nearer the Lower side. The twenty-seven outer 

 cells are in three tiers, a 



sharply marked off fro Lrs 3 is but little differ- 



ence in level between - ihird tier. There is 



noticeabl 



1 — 1 - i,1ail$j .- : first, 2 — 2 



the second line of division referable to Fig, 4 . 



A central section throu - . in the plane a — b is 



shown in fi- ,5Qfl. Ill, The peripheral cells form an arch 

 est point slightly side, and enclose a 



segmentation cavity which is almost filled with cells. The 

 two smaller cells 1 ve been cut off from the peripheral ones, 

 the larger probably from one ofits fellows. The periblast 

 ( c ,p . ) is thick and yolhy. A more pronounced large-en. 

 type is Pig, 51, "ere the segmentation cavity is somewhat 



eccentric, and , as in the preceding, the ... over- 



