Pink Floyd had moderate mainstream success and were one of the most popular bands in the London underground music scene in the late 1960s led by Syd Barrett; however, Barrett's decline in health would eventually forced his band members to replace him with guitarist and singer David Gilmour. After Barrett left the group Pink Floyd released "Ummagumma". The album was released as a double disc, the first disc contained songs performed live the other disc contained the new studio recorded songs. Singer and bass player Roger Waters gradually became the leader of the band in the mid-1970s, until 1985 when he left the group. The band recorded several albums, achieving worldwide success with "The Dark Side of the Moon" (1973), "Wish You Were Here" (1975), "Animals" (1977), and "The Wall" (1979) with all of them topping the American record chart with the exception of Animals. "The Dark Side of the Moon" is the third best-selling studio album in the world (not counting compilations and various artists soundtracks). In 1985, Waters stated that Pink Floyd was no more, but the remaining members, led by Gilmour, continued recording and touring under the name Pink Floyd. Waters sued the remaining members for the rights to the name, Waters lost and the band enjoyed worldwide success with "A Momentary Lapse of Reason" (1987) and "The Division Bell" (1994).