Before describing the new aquarium some mention should be made of the final state of the old, which was described in detail some years ago (Wilson, 1952). Various suggestions for improvement made at that time were subsequently carried out. Thus the central table tanks were removed in 1953 and the central curtains, after shortening, were hung from the ceiling above the front top edge of the south-side tanks. This gave greatly improved viewing of the tank contents through exclusion of direct daylight to the public hall, and the viewing was still further improved when the south-side windows were blackened inside and the tanks lit solely by electric light. Modifications to the reservoirs (described below) brought about a clarity of the sea water never before attained.