of Volvox globator, [127] f.
—see also Oosphere, Oosperm, Egg
Owl, blood parasites of, [120]
Oxyaster (an aster with a small centrum and oxeate actines), [222]
Oxytricha, [138]
Oxytylote (a rhabdus of which one actine is oxeate, the other tylote or knobbed, the latter directed towards the surface of the Sponge), [224]
Pachychalina, [223]
Pachymatisma, [215];