Howe & Strauss, Time and Newsweek, The New York Times, and marketing gurus everywhere have misled us. If you buy into the idea that there's any such thing as a generation, then it's simply not true that the Lost Generation (1883-1900, supposedly) was followed by a G.I./Greatest Generation (1901-24), a Silent Generation (1925-42), a Boom Generation (1943-60), a Thirteenth/X Generation (1961-81), and most recently, a Millennial Generation (1982-2003).
I was born in 1967, and this stuff has bothered me since the early '90s, when I was informed that I was an "Xer" — which meant lumping me in, first, with younger post-Boomers (whom I call the Original Generation X), and later, with older members of the Net Generation. Just like Obama says he never felt like a Boomer (he's not; he's an OGXer), I never recognized this cobbled-together, imaginary Generation X. So a couple of years ago, while blogging for The Boston Globe's Ideas section, I re-periodized and renamed several recent generations.
More recently, while blogging for io9.com about Radium (or pre-Golden) Age science fiction, I identified the following 19th- and 20th-century European and American generational cohorts: Prometheans (1844-53) | Plutonians (1854-63) | Anarcho-Symbolists (1864-73) | Psychonauts (1874-83).