The Brig Robertina, Davis, master, sailed from Fremantle, on Wednesday morning last, bound for Adelaide, with 6 passengers and a cargo composed of timber, flour, etc., and early on the same evening, about half-past 7 o’clock, she struck upon the Murray Reef, and immediately went down, head foremost, leaving about 3 feet of her stern above water. The crew and passengers escaping in her boats. Captain Davis reached Fremantle yesterday evening and reports that it is probable a portion of the cargo may be recovered. We understand that all on board had barely sufficient time to reach the boats before she went down.