Castle. — Cioua iutestiualis. 



PLATE XII. 



Magnification of all Figures, 560 diameters. 



Figs. 84-87. Four cross sections from a series through a gastrula with wide-open 



blastopore. 

 Fig. 84. Section posterior to the blastopore. 

 Fig. 85. Section through the posterior portion of the blastopore. 

 Fig. 86. Section through the anterior portion of the blastopore. 

 Fig. 87. Section anterior to the blastopore. 



Figs. 88-92. Five cross-sections through an embryo with greatly contracted blasto- 

 pore ; Figs. 88 and 89 posterior to blastopore ; Figs. 91 and 92 an- 

 terior to blastopore. 

 Note. — The large unstippled cell in the left half of Fig. 88 should have been 

 stippled. 

 Figs. 93-97. Five cross sections through a slightly older embryo. Compare vertical 

 lines 93-97 in Fig. 98. Fig. 93, section posterior to blastopore ; 

 Figs. 95-97, sections anterior to blastopore. 

 Note. — The large unstippled cell in the left half of Fig. 93 should have been 

 stippled, likewise two large cells situated laterally in Fig. 95, one in either half 

 of the Figure. 

 Fig. 98. Sagittal section through an embryo with nearly closed blastopore. 



