Six members of the Class of 1900, assisted by Professor Archibald Cary Coolidge, founded the Digamma Club in 1898. The name, the sixth letter of the old Greek alphabet, was chosen to reflect the original six members. The club became final the following year. When it became popular for clubs to disassociate themselves from fraternities and drop their Greek names, the Digamma followed suit, choosing to be called the Fox. By 1925 (and perhaps even earlier), the name had officially changed to the Fox Club.
From the description of Records of the Fox Club, 1907-1983. (Harvard University). WorldCat record id: 426074318