E YCLESH YMER. 



EXPLANATION OF PLATE XXL 



Fig. I. Meridional section of egg at stage shown in Fig. 7, PI. XX (X 45). 



Fig. 2. Section along line xy of Fig. 2, PI. XX (X 45). 



Fig. 3. Section along line xy of Fig. 3, PI. XX (X45). 



Fig. 4. Saggital section of a stage about the same as indicated in Fig. 4, 

 PI. XX (X4S). 



Fig. 5. Saggital section of egg of Petromyzon marinus at a stage indicated by 

 Fig. 10, PI. XX (X 90). 



Fig. 6. Saggital section of gastrula of Petromyzon marinus, little later than 

 Fig. 10, PI. XX. 



Fig. 7. Saggital section of Petromyzon marinus after Hatta. 



Fig. 8. Saggital section of Petromyzon marinus showing teloblast. 



Fig. 9. Transverse section of Amblystoma, at stage intermediate between 

 Figs. 4 and 5, PI. XX (X90). 



Fig. id. Section through caudal vesicle of Lophius at stage shown in Fig. 24, 

 PI. XX (Xioo). 



Fig. II. Portion of 10 marked {per.) more highly magnified. 



Fig. 12. Section across post-embryonic portion of germ-ring of Amiurus at a 

 stage indicated by Fig. 15, PI. XX (X 300). 



Fig. 13. Saggital section through posterior portion of embryo of Lophias at 

 stage indicated by Fig. 21, PI. XX (X 250). 



Fig. 14. Saggital section through posterior portion of embryo of Lophius at 

 stage indicated by Fig. 22, PI. XX (X 250). 



Fig. 15. Saggital section through same region at a later stage (X 250). 



