Orthagoriscus, [727], [153], [354];

spinal cord, [367];

O. mola, [602], [727], [348], [357]

Ortho-enteric, [102], [108]

Osmeroides, [547]

Osmerus, [566], [565];

O. eperlanus, [568];

gonoducts, [405], [411]

Osphromenidae, [669], [654];

labyrinthiform organ, [293]