414 



EYCLESHYMER. 



EXPLANATION OF PLATE XX. 



Figs. i-6. Surface views of successive stages in the formation of the embryo 

 of Amblystoma punctatum (X 15). 



Fig. I. Surface view, showing irregular depression among yolk cells at 

 vegetative pole, also first indication of blastopore (X 15). 



Figs. 2, 3. Surface views of postero-ventral surface, showing later stages 

 in extension of blastopore (X 15). 



Figs. 4, 5, 6. Surface views of postero-ventral portion, showing successive 

 stages in closure of blastopore, also the formation of neural folds (X 15). 

 Fig. 7. Ventral surface view of extremely large blastopore (X 15). 

 Figs. 8, 9. Surface views of blastopore of Rana palustris (X 15). 

 Fig. 10. Surface view of Petromyzon marinus, drawn from living egg by Dr. 

 Johnson, showing lateral extension of the blastopore (X 30). 



Figs. 11-14. Surface views of Amiurus catus, showing formation of embryo 



(Xi5)- 



Fig. 1 5. Shows portion of germ-ring left behind the embryo. 



Fig. 16. Surface view of Coregonus albus, showing late stage in closure of 

 blastopore (X 15). 



Figs. 17-24. Successive stages in the formation of the embryo of Lophius 

 piscatorius, showing the part of the germ-ring left behind (X 45). 



