ade, triforium, and clearstory. In the East, in conjunction with
the dome, these divisions survive in many examples of the later period.
Still, Byzantine architecture was more concerned with spaces than with
lines. Large surfaces for marble, painting, or mosaic were of prime
importance, and with the disappearance of the gallery the string-course
marking the level of the gallery also tended to disappear. In churches
with galleries, like S. Theodosia (p. 170) and S. Mary Diaconissa (p.
185), the string-courses fulfil their function, the first marking the
gallery level, the second the springing of the vault. In SS. Peter and
Mark (p. 193), which has no gallery, there is only one string-course,
corresponding in level to the original gallery string-course;
accordingly the main arches are highly stilted above it. The absence of
the second string-course is a faulty development, for a string-course at
the vault level would be a functional member, whereas at the gallery
level it is meaningless.

In the Panachrantos (p. 130), as well as in other churches without a
gallery, the gallery string-course is omitted by a more logical
development, and the string-course at the springing of the vault is
retained. Openings which do not cut into the vault are then frankly
arched, without impost moulding of any kind. Simple vaulted halls,
narthexes, and passages have usually a string-course at the vaulting
level, broken round shallow pilasters as at the Chora, S. Theodosia, and
the Myrelaion. Sometimes the string-courses or the pilasters or both are
omitted, and their places are respectively taken by horizontal and
vertical bands. Decorative pilasters flush with the wall are employed in
the marble incrustation of S. Sophia.

In churches of the 'four column' type the full triple division is common
but with a change in purpose. A gallery in a church of this character is
not possible, for the piers between which the gallery was placed have
dwindled into single shafts. Hence the first string-course ceases to
mark a gallery level and becomes the abacus level of the dome columns,
as in the north and in the south churches of the Pantokrator. It is then
carried round the building, and forms the impost moulding of the side
arches in the bema and of the east window. Sometimes, however, it does
not extend round the bema and apse but is confined to the central part
of the church, as in the Myrelaion, S. Theodore, and the Pantepoptes. On
the other hand,