British species, [49]

Macrostomatidae, [49]

Magelona, [325];

haemerythrin in, [252]

Magelonidae, [258], [325]

Main-gut, of Leptoplana, [8], [13];

of Polyclads, [17]

Malacobdella, [101];

description of, [119];

M. grossa, [110], [119];