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"Ambulacra of Star-fish, As seen in a longitudinal and vertical section of one of the rays; and three of them in a separate figure on a larger scale, in which they are shown in different conditions; a, a, a, tubular feet; b, b, b, internal vesicles; c, the organ which supplies the fluid with which they are filled." — Chambers' Encyclopedia, 1875

Ambulacra

"Ambulacra of Star-fish, As seen in a longitudinal and vertical section of one of the rays; and three…