Arthrostraca
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Ar`thros´tra`ca
| n. pl. | 1. | (Zool.) One of the larger divisions of Crustacea, so called because the thorax and abdomen are both segmented; Tetradecapoda. It includes the Amphipoda and Isopoda. |
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.