834 Puget Sound Marine Sta. Pub. Vol. 1, No. 28 



PLATE 75 

 6c?=blastoderm 

 ti^embryonic thickening 

 f/r^germ ring 

 /ie=head end of embryo 

 rrts^mesodermal somites 

 oz;=optie vesicle 

 p*=primitive streak 

 v/=yolk 

 Fig. 13. Surface view of 5-day egg from above; beginning of germ 

 ring. X 7.6. 



Fig. 1 i. Surface view of 6-day egg from above; germ ring; embry- 

 onic thickening. X 7.6. 



Fig. 15. Surface view of 7-day egg from above; germ ring; em- 

 bryonic thickening. X 7.6. 



Fig. 16. Surface view of 8-day egg from above; germ ring; primor- 

 dium of head. X 7.6. 



Fig. 17. Surface view of 8-day egg from side; germ ring; primor- 

 dium of head. X 7.6. 



Fig. 18. Surface view of 9-day egg from side; germ ring advancing. 

 X 7.6. 



