The Cleveland Spiders were folded into the St. Louis Perfectos sometime during the 1899 season and the combined franchise became the Cardinals the following year. It's detailed in the biography of Tris Speaker that came out a couple years ago. It's also in the commemorative "100 years of Cleveland Indians" book that was sent out to season-ticket holders in the 2001 season. Unfortunately I don't have either book handy to give the minutae, but the Spiders were bleeding money and the NL wanted to strengthen the St. Louis franchise, so they merged the sorry Spiders (who went 20-134) into the Perfectos. Note that any player of consequence for the 1899 Spiders wound up playing for the Cards in 1900--Lave Cross, Ossie Schreckengost, Willie Sudhoff. It also gets you access to Cy Young for the Cardinals in franchise leagues, as he pitched for the 1898 Spiders.