BAIRDIELLA CHRYSURA AND ANCHOVIA MITCHILLI. 



dorsal and dorso-lateral aspects of the embryo. A few yellow chromatophores are appar- 

 ent also on the surface of the oil globule. The distribution of chromatophores at this 

 stage is illustrated in figures 12 and 13. Kupffer's vesicle (fig. 13, Kv) now appears as 

 a small bubblelike body on the ventral surface near the posterior end of the embryo. 



BAIRDIELLA CHRYSUR.\. 



Fig. 12. — Early embryo showing distribution 

 of chromatophores. dorsal view. X ss- 



Fig. 13. — Early embryo showing distribution of 

 chromatophores; Kv, Kupfler's vesicle. X 55. 

 Lateral view. 



An hour later (fig. 14) the chromatophores have become more numerous and are 

 distributed more or less uniformly over the entire dorsal and lateral surfaces of the 

 embryo. Kupffer's vesicle has now reached its maximum development. After this it 

 gradually decreases in size until it disappears. The length of the embryo now exceeds 

 half the circumference of the yolk sphere and shows 10 to 12 somites. 



As development advances and the time of hatching approaches, the distribution of 

 the chromatophores undergoes a material change. A few hours before hatching the 



.—^f—Yof/ 



BAIRDIELLA CHRYSURA. 



Fig. 15. — Egg with advanced embryo. X 55. 



Fig. 14. — Egg with embryo showing 10 somites; Kv, 

 Kupfler's vesicle. X 55. 



embryo becomes quite active within the egg membrane. The posterior portion of the 

 body is now free from the yolk sphere and narrow fin folds are apparent both dorsally 

 and ventrally (fig. 15). 



Larval development. — At the time of hatching the larval fishes are 1.5 to 1.8 mm. 

 in length. The head is slightly deflected at the anterior end of the large oval yolk sac. 



