86 



Conservation Department 



2, 4, and 8 cell stages being apparent at this time. Blastodisc 

 lenticular by 5th day uith oil glolndes congregated beloAv. On 



Fig. 11. — Coregonus clupeaformis egg 

 immediately after fertilization 



26th day an early embryo, reaching halfway aronnd egg, showing 

 well developed optic vesicles slightly pigmented on inner and 

 upper margins and oil globules coalescing to form usually about 2 

 very large bubbles Avith many small ones remaining. At 40 days 

 embryo completely around egg ; head much higher and more 

 rounded, eye larger and black ; 1 large oil globule on yolk and 

 only a few smaller ones. First evidence of dorsal and ventral 

 marginal pigmentation evident at 54 days. 



Fig. 12. Coreiiomis clupeaformis egg with larva emerging 



Fig. 12 shows Ihc (Mn])ry() in ])rocess of hatching on the 61st 

 day. Mouth is not oj)cn ; vent at a distance from body, at edge 

 of fin; cMiliryonic marginal fin completely encircling fish from 

 behind head around lophocercal tail to yolk sac; yolk sac very 

 large, dee]) yellowish in color, with 1 large oil globule and other 

 smaller ones. Myomeres completely formed. Double series of 



