Petro-Canada, Calgary, (NYSE: PCZ; Toronto: PCA) has dropped out of the bidding war for Canada Southern Petroleum Ltd., Calgary, (Toronto: CSW; Nasdaq: CSPLF) following a US$13.10-per-share offering from Canadian Oil Sands Ltd., a subsidiary of Canadian Oil Sands Trust, Calgary, (Toronto: COS.UN) valued at approximately US$190 million. Petro-Canada, through its subsidiary Nosara Holdings Ltd., had last bid US$13 per share for Canada Southern. The company reports that it does not intend to up its offer again, and will let it expire, as previously announced, on July 27. Canada Southern has estimated gas reserves in the Arctic Island of 927 billion cubic feet equivalent. It also holds reserves in southern Yukon and northeastern British Columbia currently producing 6 million cubic feet per day.