Ambulacrum
Pronunciation : Am`bu*la"crum
Part of Speech : n.; pl. Ambulacra.
Etymology : [L., an alley or covered way.] (Zo?l.) (a) One of the radical zones of echinoderms, along which run the principal nerves, blood vessels, and water tubes. These zones usually bear rows of locomotive suckers or tentacles, which protrude from regular pores.
Source : Webster's Unabridged Dictionary, 1913