Dosinia discus (Heeve). 583 



sort, though less marked, were noted. In every instance both valves 

 were equally deformed. 



Summary. 



The shell of Dosinia discus (Reeve) between the lengths of 

 1,5 and 7,5 cm grows in such a manner that the increase in its 

 depth, Avidth, interadductor distance and depth of palliai sinus are 

 directly proportional to the increase in its maximum length. The 

 sum of the width of the two valves, plus the depth, divided by the 

 length of the shell, is approximately constant. 



