FIQ. 38
FIG. 38. Distribution of Clava squamata in July 1955. 0, absent; @, present.
FIG. 39. Distribution of Aecophyllum nodoeum in July 1955. 0, absent; 0 , up to 25%; C , 26-50; 0 , over 50.
FIG. 40. Distribution of Littorim liltoralis in July 1955. 0, absent; @, present.
FIG. 40