MUSEUM OF COMPARATIVE ZOOLOGY. 97 



PLATE III. 



Fig. 9. Cross section cut f mm. from anterior end of embryo, seven days old, 



1| mm. long. 

 " 10. Cross section cut j^g mm. from anterior end of embryo, seven and one half 



days old, If mm. long. 

 " 11. Cross section cut y'^ mm. from anterior end of embryo, eirjht days and 



four hours old, 2f mm. long. 

 " 12. Cross section cut | mm. from anterior end oi fundulus embryo,/o«r and 



one half days old, 2j'jj mm. long. 



PLATE IV. 



Fig. 13. Cross section of a fundulus embryo, six hours younger than that of Figure 



12. Cut in tiie same region. 

 " 14 and 15. Cross sections of the same fundulus embryo as tliat of Figure 13, 



and from nearly the same region. 

 " 16. Cross section tlirougii tlie heart of a cod embryo, nine and one half days 



old. 



PLATE V. 



Diagram of an apparatus for hatching fish eggs. For explanation, see text, 

 pages 93, 94. 



