been reserved almost exclusively
for nave pillars, as at Torcello, Murano, and St. Mark's; it occurs,
indeed, together with almost every other form, on the exterior of St.
Mark's also, but never so definitely as in the nave and transept shafts.
Of the conditions assumed by it at Torcello enough has been said; and
one of the most delicate of the varieties occurring in St. Mark's is
given in Plate VIII., fig. 15, remarkable for the cutting of the sharp
thistle-like leaves into open relief, so that the light sometimes shines
through them from behind, and for the beautiful curling of the
extremities of the leaves outwards, joining each other at the top, as in
an undivided flower.

Sec. XVI. The other characteristic examples of the concave groups in the
Byzantine times are as simple as those resulting from the Corinthian are
rich. They occur on the _small_ shafts at the flanks of the Fondaco de'
Turchi, the Casa Farsetti, Casa Loredan, Terraced House, and upper
story of the Madonnetta House, in forms so exactly similar that the two
figures 1 and 2 in Plate VIII. may sufficiently represent them all. They
consist merely of portions cut out of the plinths or string-courses
which run along all the faces of these palaces, by four truncations in
the form of arrowy leaves (fig. 1, Fondaco de' Turchi), and the whole
rounded a little at the bottom so as to fit the shaft. When they occur
between two arches they assume the form of the group fig. 2 (Terraced
House). Fig. 3 is from the central arches of the Casa Farsetti, and is
only given because either it is a later restoration or a form absolutely
unique in the Byzantine period.

[Illustration: Plate VII.
BYZANTINE CAPITALS. CONVEX GROUP.]

Sec. XVII. The concave group, however, was not naturally pleasing to the
Byzantine mind. Its own favorite capital was of the bold convex or
cushion shape, so conspicuous in all the buildings of the period that I
have devoted Plate VII., opposite, entirely to its illustration. The
form in which it is first used is practically obtained from a square
block laid on the head of the shaft (fig. 1, Plate VII.), by first
cutting off the lower corners, as in fig. 2, and then rounding the
edges, as in fig. 3; this gives us the bell stone: on this is laid a
simple abacus, as seen in fig. 4, which is the actual form used in the
upper arcade of Murano, and the framework of the capital is complete.
Fig. 5 shows the general manner and effect of