242 WILSON. 
DESCRIPTION OF PLATE II. 
Fic. 1. Section through a blastosphere. C, 4. 
Fic. 2. Section through delaminating blastosphere. C, 4. 
Fic. 3. Part of another blastosphere such as Fig. 2. D, 4. 
Fic. 4. Median long. sec. through a solid planula with commencing cesophagus. 
Cia: ; 
Fic. 5. Long. sec. through a larva in which the permanent layers are forming. 
Core 
Fic. 6. Long. sec. of slightly older stage. Position of cesophagus is eccentric. 
Cra: 
Fic. 7. Trans. sec., through cesophagus, of larva at about the stage of Fig.5. The 
formation of the permanent layers is not so far advanced as in the latter figure. D, 4. 
Fic. 8. Long. sec. through a larva in which the cesophagus has opened cen- 
trally. D, 4. 
Fic. 9. Trans. sec. through a larva in which the cesophagus is still more eccentric 
than in Fig. 8. The section is through line @ in Fig. 8. D, 4. 
Fic. 10. Trans. sec. of same larva at lower level, through line 4 in Fig. 8. D, 4. 
