n of the two forms is of great importance for the study of
certain Constantinople churches.

[Illustration: FIG. 1.--KASR IBN WARDAN (Strzygowski).]

The domed basilica, as the name indicates, is a basilica with nave and
aisles, in which a square bay in the centre of the nave is covered by a
dome on pendentives. To north and south, within the arches supporting
the dome, appear the nave and gallery arcades of the basilica; and as
the galleried basilica is a usual Eastern form galleries are usual in
the domed basilica. As seen from the central area, therefore, the north
and south dome arches are filled in with arcades in two stories, and the
side aisles and galleries are covered with barrel vaults running
parallel to the axis of the church. At the west end a gallery over the
narthex may unite the two side galleries. At Kasr ibn Wardan, instanced
by Strzygowski as a typical domed basilica,[15] there is such a western
gallery (Fig. 1). According to Strzygowski the domed basilica is older
than the fifth century.

The domed basilica remains always an oblong building, and whilst the two
sides to north and south are symmetrical, the western end retains the
basilican characteristics--it has no gallery or arcade communicating
with the central area. The narthex communicates with the nave by doors,
and if a gallery is placed above it, both narthex and gallery are
covered by barrel vaults.

In the domed cross church (_Kreutzkueppelkirche_) the central dome rests
on barrel vaults which extend to the outer walls of the building and
form the arms of the cross, the eastern arm forming the bema. The
lighting of the church is by windows in the gable walls which terminate
the north, south, and west cross arms. The prothesis and diaconicon open
off the side arms, and two small chambers in the western angles of the
cross bring the plan externally to the usual rectangular form.

The domed cross church may have galleries, as in S. Theodosia (p. 170),
or may be without them, as in SS. Peter and Mark (p. 193). Where
galleries are present they are placed in the cross arms and are
supported by arcades at the ground level. The vaults beneath the
galleries are cross-groined. The domed cross church is a centrally
planned church, in contrast to the domed basilica, which is oblong, and
therefore we should expect that where galleries are used they will be
formed in all three arms of the cross, as is the case in S. Theodosia.

There are a number