Sentence:  ANAIMONA, Aquatilia Exanguia, "Bloodless" Fishes, are divided into "Mollia" Soft Fishes without Shells; Crustata, those that are covered with thin pliant Shells; and <WSD>Testacea</WSD>, those which have thick, hard brittle Shells. 
Meaning of the word marked with <WSD> tags:  Any of various shellfish, especially those of the obsolete orders Vermes or Acephala, or the suborder (suborder).