36 



D. A. HANCOCK AND A. C. SIMPSON 



^ 40- 

 UJ 30. 



23 OCT. 56 



^ 20H 



X 

 O lo- 



z 



uJ 



-J 



— I — 



20 



— I — 

 30 



— I — 

 50 



lO 20 30 40 50 60 



LENGTH OF SHELLS mm. 



Fig, 4. — Penis lengths of whelks from Whitstable, October 1956. 



— I — 

 70 



2 60- 



23 OCT. 1956 



384 (f(?- small p«nU 

 D 2 with thickened shells 



161 W - large penis 

 With thickened shells 



628^? 

 with thickened shells 



10 20 30 40 50 60 70 80 90 



LENGTH OF SHELL-mm. 

 Fig. 5. — Length distribution of whelks from Whitstable, October 1956. 



