ostraco-before a vowel ostrac-, combining form of Gr. ὄστρακον hard shell.Hence ostraˈcology[see -logy], conchology (Mayne); so ˌostracoˈlogicala.ˈostracoˌphore[Gr. -ϕορος bearing], a member of the Ostracophori, a Palæozoic sub-class of fishes (Funk); so ostraˈcophorousa.ˈostracoˌpod, a member of the Ostracopoda, an order of entomostracous crustacea; so ostraˈcopodousa., belonging to the Ostracopoda (Mayne). ostraˈcostean[Gr. ὄστεον bone]a., pertaining to the Ostracostei, a group of extinct placoganoid fishes; n. a fish belonging to this group; so ostraˈcosteousa.ˈostracoˌthere[Gr. θήρ animal], an ostracode crustacean.1876tr.Beneden's Anim. Parasites 17 Since the molluscs live only on vegetable substances, while the Ostracotheres feed entirely on animal matter.