Subway Access
Just as you enter from the Industrial District, hurdle over the pipe in front of you and just before the hole in the ground should be some chattering teeth.
Continue down the previous hall and take the first left. More teeth should be on the ground before the next gap (that you'll line launch over).
Drop down to the bridge below after the previous set of teeth and then go forward. Turn right at the intersection and slide under the gate. There should be more teeth at your feet.
The last set of teeth in this area is the intersection just before where you drop into the Subway Terminal.
Subway Terminal
Just after dropping into the terminal from Subway Access, turn around and you should see the teeth by the barrels.
On the northern platform, you will find chattering teeth by the base of the stairs on the west side of the platform.
By the southwestern exit to this area (where you need to open a shutter with the REC), you should find a set of teeth on the ground.
In the tunnel leading toward Wonder Tower, these teeth are located just before the door to Wonder Tower Fondation.
Subway Tunnel
You'll find this on top of one of the cars in the northern tunnel near some pipes you must slide under.
This is by the western end of the southern tunnel, just before you climb through the vent into the Subway Station.
Subway Station
On the bottom floor, you'll find teeth at the west end, between the tracks.
On the top floor by the doors to the south, there are two rooms. In the room to the right will be chattering teeth on the floor by a dead body.
