On Saturday, September 10, 1966, the Family Dog's FD-25 poster closed its two-night stand at the Avalon Ballroom: Quicksilver Messenger Service over the Great Society — Grace Slick's band, still a year or so before she carried "Somebody to Love" and "White Rabbit" over to the Jefferson Airplane. This was night two of the Friday–Saturday run the Dog dated September 9–10, and the poster is one of the era's quiet touchstones — Alton Kelley's concept executed by Stanley Mouse, the image adapting an Edward S. Curtis photograph into that Curtis-plate solemnity the two would keep mining (catalog, bill, and the two-night dating per coau and wolfgangs, poster attribution corroborated on rockposters). It is a small, telling bill: the house band that would become Quicksilver on top, and beneath them the group whose singer was about to change which marquee she stood under.

A year on, the Avalon was still the Dog's room, and September 10 fell inside another of its runs. FD-80 — the one the Family Dog nicknamed the "Tea Party," with Greg Irons handling the poster — reached the last of its three nights on Sunday, September 10, 1967. The bill across the September 8–10 span read Southside Sound System, the Phoenix, and Freedom Highway; which of those actually took the Sunday isn't something to pin down from the printed sheet, so the honest thing is to leave the whole run bill standing rather than crown a headliner for the closing night (dates and bill per wolfgangs and rockposters, with the poster held in the Smithsonian American Art Museum's collection).

Back in 1966, the Avalon wasn't the only place in town with music on the calendar. Over at the Matrix, the Blues Project was in the middle of a residency that ran September 7–15 — the stretch later documented by the released "Live at the Matrix September 1966" tapes, which is how we know the band was in the room across those nights at all. September 10 sits squarely in the middle of it, so treat it as a residency night and nothing more precise; there's no Sep-10-specific setlist to lean on, and it would be inventing detail to claim one (residency window per the released Matrix recordings).

By 1969 the map had shifted west and gotten busier. On Wednesday, September 10, the Incredible String Band played a midweek one-off at Fillmore West — the night before Bill Graham's BG-191 run (Steve Miller, James Cotton, Keef Hartley) opened on the 11th. The show is ticket-documented, but there's a trap worth naming: there is no confirmed poster for this September 10 ISB night. The Pat Hanks String Band poster people sometimes reach for (the BG-ISBg-1) belongs to a separate December 10, 1969 show and does not attach here — so this one goes in the ledger as a ticketed date without art.

And the same night, out at the ocean end of town, the Family Dog on the Great Highway ran one of its themed midweek evenings — a "Latin Rock" bill of Kwane and the Kwanditos with Los Flamencos de la Santa Lucia (per rockarchaeology101). There's no printed poster to hang on it; the FD-6909xx-style codes that float around these Great Highway dates are date-stamps, not catalog numbers, and shouldn't be mistaken for one.

(1967: FD-80's "Tea Party" closed at the Avalon, the run told above. Two 1969 shows share the date — the Incredible String Band's posterless one-off at Fillmore West, and the Great Highway's Latin Rock night — both midweek, both undocumented by any printed sheet. 1965: no verifiable San Francisco ballroom event on this date — the scene hadn't gathered yet.)