ELASMOBRANCHII 



[CH. 



living representatives of this family have x been found in the Lias 

 shales of England. The Port Jackson Shark of Australia Cestracion, 

 is the sole surviving type of another family (the Heterodontidae), 



. 228. A. Scyllium canicula. Eeduced. From Day. 

 B. Egg-case opened to show young embryo with yolk sac. 



