This paper presents comparative research on marine shell from four 19th century historical archaeological sites in Melbourne. The shell derives predominantly from Mud Oyster (Ostrea angasi) and Sydney Rock Oyster (Saccostrea glomerata) commercially harvested from natural reefs along the south-east Australian coastline. The research collects quantitative data that informs on the 19(th) century oyster industry and investigates inter-site shell variability and its implications for processing, consumption and discard. Dredging of subtidal reefs provides an explanation for the numerical dominance of oyster, the presence of subfossil cultch (Anadara) and the wide range of minor shellfish. Mud oyster and Sydney rock oyster comparisons in valve size, sided counts and preservation record significant differences within and between sites due to the origins, depositional conditions and the processing of the shell. These data form the basis of two models. The first predicts the archaeological representation of reef dredging and ranks shellfish according to categories, from live oysters to dead shell sampled from the reef substrate. Based on oyster shell anatomy and the separate uses of the right (lid) and left (dish) valves, the second model considers how oyster processing and consumption is characterised archaeologically in differential valve counts and pairing rates.
