Castle. — Ciona iutestiualis. 



PLATE XIII. 



Magnification of all Figures, 5G0 liiameters. 



Figs. 99-105. Seven sections t'lom a series througii an embryo witli completely 

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

 of blastopore ; Figs. 10o-105, anterior to region of closure of 

 blastopore. 



Fig. 106. Cross section tiirougli an early larval stage (unliatched). Tiie trunk 

 region is sliown in the left portion of tiie Figure, tlie tail region in 

 the right portion. 



