BULLETIN OF THE UNITED STATES FISH COMMISSION. 1G5 



sg. Segmeutation cavity. 

 so. Somites or segments of tlie muscle plates. 

 ss. Supracephalic sinus. 

 ir. Trabeculic crauii. 

 V. Vent. 

 ve. Ventricle. 

 wd. WolfSan dnct. 

 zr. Egg-membrane. 

 2/. Yelk. 



