A 



10 15 20 



SHELL HEIGHT (MM) 



10 15 20 25 



SHELL HEIGHT (MM) 



B 



10 15 20 25 



LENGTH OF VALVE(MM) 



5 

 z 10 



UJ 



15 20 25 



LENGTH OF VALVE (MM) 



X 



< 



16 18 20 



VALVE HEIGHT (MM) 



X 



< 

 2 



14 



16 18 20 



VALVE HEIGHT (MM) 



22 



24 



Fig. 13. — Ontogeny in Lopha lugubris (Conrad). A, Relationship between 

 valve height and the amount of dorsal and lateral margin covered with denticles, 

 measured parallel to valve height. B, Relationship between the length of the 

 hinge line and the length of the valve. C, Relationship between the maximum 

 diameter of the muscle scar and the height of the valve. All lines fitted visually. 

 Approximate boundaries between ontogenetic stages marked by dashed lines. 

 E = Ephebic ; G =: Gerontic ; R = Right valve ; L = Left valve. 



40 



