The whole early architecture of Venice is architecture of incrustation: this has not been enough noticed in its peculiar relation to that of the rest of Italy. There is, indeed, much incrusted architecture throughout Italy, in elaborate ecclesiastical work, but there is more which is frankly of brick, or thoroughly of stone. But the Venetian habitually incrusted his work with nacre; he built his houses, even the meanest, as if he had been a shell-fish,--roughly inside, mother-of-pearl on the surface: he was content, perforce, to gather the clay of the Brenta banks, and bake it into brick for his substance of wall; but he overlaid it with the wealth of ocean, with the most precious foreign marbles. You might fancy early Venice one wilderness of brick, which a petrifying sea had beaten upon till it coated it with marble: at first a dark city--washed white by the sea foam. And I told you before that it was also a city of shafts and arches, and that its dwellings were raised upon continuous arcades, among which the sea waves wandered. Hence the thoughts of its builders were early and constantly directed to the incrustation of arches. [Illustration: Fig. LVII.] § XII. In Fig. LVII. I have given two of these Byzantine stilted arches: the one on the right, _a_, as they now too often appear, in its bare brickwork; that on the left, with its alabaster covering, literally marble defensive armor, riveted together in pieces, which follow the contours of the building. Now, on the wall, these pieces are mere flat slabs cut to the arch outline; but under the soffit of the arch the marble mail is curved, often cut singularly thin, like bent tiles, and fitted together so that the pieces would sustain each other even without rivets. It is of course desirable that this thin sub-arch of marble should project enough to sustain the facing of the wall; and the reader will see, in Fig. LVII., that its edge forms a kind of narrow band round the arch (_b_), a band which the least enrichment would render a valuable decorative feature. Now this band is, of course, if the soffit-pieces project a little beyond the face of the wall-pieces, a mere fillet, like the wooden gunwale in Plate IX.; and the question is, how to enrich it most wisely. It might easily have been dogtoothed, but the Byzantine architects had not invented the dogtooth, and would not have used it here, if they had; for the dogtooth cannot be employed alone, especially on so principal an angle as this of the main arches, without giving to the whole building a peculiar look, which I can not otherwise describe than as being to the eye, exactly what untempered acid is to the tongue. The mere dogtooth is an _acid_ moulding, and can only be used in certain mingling with others, to give them piquancy; never alone. What, then, will be the next easiest method of giving interest to the fillet? [Illustration: Fig. LVIII.]