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The ribs were ten on a side. The first, to begin from the neck, was nearly six feet long; the second, third, and fourth were each successively longer, till you came to the climax of the fifth, or one of the middle ribs, which measured eight feet and some inches. From that part, the remaining ribs diminished, till the tenth and last only spanned five feet and some inches. In general thickness, they all bore a seemly correspondence to their length. The middle ribs were the most arched. In some of the Arsacides they are used for beams whereon to lay foot-path bridges over small streams.