Definition of "testaceous" [tes•ta•ceous]

• Biology Having a hard shell or shell-like outer covering: testaceous echinoderms. (adjective)
• Biology Composed of a shell or shell-like material: a testaceous operculum. (adjective)
• Having the reddish-brown or brownish-yellow hue of bricks. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "From IV 2-10 he discusses the parts, both internal and external, of the ˜bloodless™ animals, i.e. the crustaceans, testaceous mollusks, cephalopods and insects."
• "The foregoing remarks appear to apply to the case of the Mollusca, which, at a very early period, had reached a high organization and a great development of forms and species in the testaceous Cephalopoda."
• "Crabs also slough off their old-age; this is generally allowed with regard to the soft-shelled crabs, and it is said to be the case with the testaceous kind, as for instance with the large ‘granny’ crab."