British species, [49]

Mesostomatidae, [49]

Mesotrochal larva, [325]

Mesozoa, [92] f.

Metamerism, [249]

Metamorphosis, in Polycladida, [16], [28];

in Trematodes, [5], [66] f.;

in Cestodes, [5], [74], [76], [87]-89;

in Phoronis, [459];

in Polyzoa, [512]