 Speusippus in book II of Likes says that trumpet-shells, purple-fish, snails, and clams are similar. … Again, Speusippus enumerates next in order, in a separate division, clams, scallops, mussels, pinnas, razorfish, and in another class oysters, limpets. (Athenaeus III 86c,d; Gulick 1927 pp. 372, 273.)