Castle. — Ciona intestiualis. 



PLATE XIII. 



Magnification of all Figures, 500 diameters. 



Figs. 99-105. Seven sections from a series through an embryo with completely 

 closed blastopore. Figs. 99-101, posterior to region of final closure 

 of blastopore ; Figs. 103-105, anterior to region of closure of 

 blastopore. 



Fig. 106. Cross section through an early larval stage (unhatched). The trunk 

 region is shown in the left portion of the Figure, the tail region in 

 the right portion. 



