Ruth : Development of T-vvins etc.] 



[Phil. Journ. Sci., XI, B, No. 3. 



Fig. 1. Dorsal view of duck twins, set I. 



(10 



mg 



<(* 



hpd 





K If 



Fig. 2. Dorsal view of duck twins, set IV. 

 PLATE III. 



