The defective nature of the rock below forbade the excavation of the sepulchral chamber; there was no resource, therefore, except to hide it in the brickwork.

An oven-shaped chamber with "corbel" vault was constructed in the centre (fig.
144); but more frequently the sepulchral chamber is found to be half above ground in the mastaba and half sunk in the foundations, the vaulted space above being left only to relieve the weight (fig.

145).

In many cases there was no external chapel; the stela, placed in the basement, or set in the outer face, alone marking the place of offering.

In other instances a square vestibule was constructed in front of the tomb where the relations assembled (fig.