What a great photo! I live on the SF Bay and sometimes imagine what it was like when PBYs were a common sight overhead.
Only the first PBYs (PBY-1s) had these notched elevators. I'll leave it to you to match the shadows with the planes, but the middle 3-plane section in the upper-left seems to be short a plane. (That tiny speck is a flaw in the photo.) From another photo I've seen (80-G-418203), I think plane #2 is to the left and behind plane #1.
The six planes in the lead (shadows barely visible in front of plane #3's starboard wing) are already past the bridge. These don't appear to be PBYs - perhaps they are P2Y-1s (very near the end of their service life).
BY: USN PHOTO
UNIT: PATWING TWO
PLACE: GOLDEN GATE
TAKEN 27 MAY 1937 DURING GOLDEN GATE DEDICATION
(Photo from the R.L.Lawson collection, courtesy of the Nat'l Museum of Naval Aviation)