There are eight coded hieroglyphics to be found and decoded. I'll list the locations in the order you run across them; except for the one in the scarab room, the decoding is up to you.
Tunnel 3: Right of the door leading out of the room with the scarab puzzle
First burial chamber:
-- Above the lamp
-- On coffin 1
-- On coffin 2
-- Inside coffin 2 (after you reassemble the parchment scraps)
Main room: Behind the scaffolding (after Abdullah leaves)
Cat tomb: On the central pillar under the scale puzzle
Inner tomb: Plaque held by statue to the left of the door to the Destiny tiles
