Webster's Revised Unabridged Dictionary · 1913

Pectostraca

Pectostraca (pek*tos"trȧ*kȧ) , proper noun, plural

[New Latin, from Greek phkto`s fixed + 'o`strakon shell of a testacean.]

(Zoology) A degenerate order of Crustacea, including the Rhizocephala and Cirripedia.