of Polystomum, [57];

of Distomum, [62];

absence of, in Cestodes, [74];

of Nemertinea, [103], [103], [104];

of Nematoda, [130];

of Gordiidae, [166], [169];

of Chaetognatha, [187];

of Rotifers, etc., [209], [233], [237];

of Archiannelida, [243];

of Polychaeta, [249], [269];