590 EEPOKT OF COMMISSIONER OF FISH AND FISHERIES. [134] 



EXPLANATION OF PLATE VII. 



Fig. 31. Embryo cod fourteen days after impregnation, seen from the side in section, 

 showing the optic cup op, with the choroid fissure/c entering it below. The 

 rudimental intestine is already clearly defined, and the hinder extremity 

 of the chorda dorsalis ch is enlarged, and composed of small cells, while 

 the anterior portion is hyaline, inclosing transversely placed lenticular 

 nuclei. Kupflfer's vesicle is present, and stellate pigment cells have made 

 their appearance, x 55. 



Fig. 32. Embryo cod sixteen days after impregnation, viewed from the side in section. 

 The tail has become free and is twisted over to one side, lying with one 

 of its sides against the yelk and the other against the vitelline membrane 

 The rudiment of the liver lias made its appearance as a thickening of the 

 ventral wall of the primitire intestine, at the hinder extremity of which 

 the position of the vent, has been defined. The lateral fin-fold ff is now 

 distinctly developed as a short longitudinal ridge, x 55. 



