F\ 



FIG. 14. A, hybrid larva of Spharechinus $ , and Echinus $ ; front 

 view. B, the same ; oblique, side view. C, dwarf hybrid larva of 

 Spharechinus $ (non-nucleated egg fragment), and Echinus S , of 

 pure Echinus type. D, the same larva in side view. (After 



189 



lioveri.) 



