It is possible that the ship that went missing was the 1876 built Glenfinnart which sailed from Greenock in Scotland in August 1890 for San Francisco and was never heard of again.
The Allan Line, more properly the Montreal Ocean Steamship Company, was founded in 1854 and began sailing in 1855. They continued to sail until about 1911 when negotiations with the Canadian Pacific Line took place. The company was merged with CP and became known as the Canadian Pacific Ocean Services Limited in 1915. However, it was not until 1917 that an official announcement of the merger finally became public.
Charles Orr's Memoirs Volume 2