e only the threshold is
left. These doorways must have communicated with the outer world to the
east of the church, like the doorways which occupy a similar position in
the Studion (p. 53). The northern compartment had an opening, which is
still surmounted by architrave and cornice, also in its north wall.
There are, moreover, four other openings or recesses in the northern
wall of the church, and two in the southern.

The main portions of the aisles are divided from the nave by light
screens of columns, the eastern and western portions being connected by
passages driven through the dome piers. In the eastern nave bay there
are four columns, giving five aisle bays on each side. The columns are
very slender, without any base moulding, and stand upon square
pedestals, now framed round with Turkish woodwork. On opening one of
these frames the pedestal was found to be a mutilated and imperfectly
squared block of stone. Such blocks may have served as the core of a
marble lining, or may be damaged material re-used.

The capitals are of the 'Pseudo-Ionic' type, with roughly cut Ionic
volutes. The sinking on their lower bed is too large for the necks of
the columns. Towards the aisles they bear the monograms of Justinian and
Theodora, identical with the monograms of these sovereigns in S. Sophia,
while on the side towards the nave they have a cross in low relief.
Usually monograms are placed in the more conspicuous position.

Above the capitals the vaulting that covers the aisles and supports the
galleries is of an uncommon type. Towards the nave the arches are narrow
and raised upon very high stilts; from each capital a semicircular arch
is thrown across to the outer wall, where is a range of windows, each of
which has an extrados at a slightly higher level than the extrados of
the corresponding nave arch; and thus a long narrow space is left
between the four arches of each vault compartment that could be filled,
wholly or in part, without the use of centering. The result is a narrow,
irregularly curved vault, shaped to the backs of each of its
surrounding arches, and having, in the main, the character of a
spherical fragment.

The western portion of each aisle is divided from the nave by an
irregular arcade supported by a pier and one column, and, consequently,
there are three aisle bays to the western nave bay, and not four as
shown by Salzenburg.

The whole interior surfaces of the walls, up to the level of the
spring