Comments:

Storrow was a surgeon with the rank of major in the Medical Department and was a patient at the military hospital on Angel Island.  Prior to his arrival at the island post, Storrow served at Fort Laramie in Wyoming (A scan of a letter written by Storrow in 1878 can be viewed on another website [click here]).

The surname carved on the post-WWI style headstone is incorrect. The name is correctly listed as "Storrow" in both the US Department of Veteran's Affairs Nationwide Gravesite Locator and the U.S. Department of Veteran's Affairs Database  (as of 
January, 2005). Further corroboration is given by records at the 
National Archives, published genealogies & military histories, and 
family records held by surviving relatives.

The following information for Maj. Storrow was graciously provided by a relative :

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"Military Record of Civilian Appointments in The United States Army", Guy V. Henry, Carleton Co, New York, 1869, page 116:

Appointed from the District of Columbia.
Assistant Surgeon U. S. Army, August, 1861. At Fort Washington, Md., to July, 1862. Hospital duty, Washington D.C., to April, 1863. With the Army of the Potomac, to March, 1864 Hospital duty, Philadelphia, to October, 1864. Officer's Hospital, Philadelphia, to July, 1865. Mower Hospital, Philadelphia, to September, 1865.  Hospital duty, Nashville, Tenn., to March, 1866. Taylor Barracks, Louisville, Ky., to April, 1868. Brevet Captain and Major U. S. Army, for faithful and meritorious services during the war. At Fort Jefferson, Tortugas, Fla., from April, 1868, to --- {book published in 1869}.
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The following site:
http://www.nps.gov/fola/doctors.htm
shows him as post surgeon at Fort Laramie, Wyoming from Jan. 11, 1878-May 30, 1879.

Four weeks later, the following judgement was rendered: (correspondence from the National Archives)
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San Francisco, Cal
July 5th 1879

Surgeon General
U.S. Army
Washington D.C.

Sir
On Thursday, June 26th Surgeon Samuel A. Storrow, U.S. Army arrived in the city and sent for me to wait upon him.

{long-list of symptoms deleted}

I do not think it probable that he will ever again be able to perform any duty, and that a medical officer will be required to take his place in the Department of the Platte.(*)  Indeed I'm of opinion that his term of residence on earth is fast coming to an end.

Your Obed. Servant
Geo. E. Cooper,
Asst: _____? USA
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(*) Department of the Platte: eg, Fort Laramie, Wyoming.

[Note: George E. Cooper is interred in GGNC plot E425]
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From "The San Francisco Call", 14 July, 1879; Page 4/4

DIED

...
STORROW --In this city, July 12, Samuel Appleton Storrow, of the U.S. Army, aged 48 years.  Friends who wish to attend his funeral will take the Quartermaster's steamer, which will leave Washington street wharf TO-DAY (Monday), at 3 o'clock P.M. Interrment, Angel Island.
...

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Samuel's father, also named Samuel Appleton Storrow, was one of only two divisional Judge Advocates in the U.S. Army at the time, serving from 1815-1820, and attaining the rank of Judge Advocate Major. He was attached to the Northern Department (division), serving under Major General Jacob Jennings Brown. Major General Edwin Vose Sumner (later of Civil War fame) was a personal friend of Samuel (the elder) and in honor of their friendship named one of his sons Samuel Storrow Sumner - who 
later served in the Civil War, the Spanish American War, etc, and 
achieved the rank of Major General. General Samuel Storrow Sumner is buried at Arlington National Cemetery. 

General Edwin Vose Sumner played a role in securing a military 
appointment for Surgeon Major Samuel Storrow.