Tes*ta"ceous (?), a. [L. testaceus, fr. testa a shell. See Testa.]
Of or pertaining to shells; consisted of a hard shell, or having a hard shell.
2. Bot. & Zool.
Having a dull red brick color or a brownish yellow color.
Testaceous animals Zool., animals having a firm, calcareous shell, as oysters and clams, thus distinguished from crustaceous animals, whose shells are more thin and soft, and consist of several joints, or articulations, as lobsters and crabs.
© Webster 1913.