Infection in Nature.

The Glochidia are ripe from the end of November to the end of January. The adults have been found to frequent the stony beds of several small lakes in West Canterbury, notably Lake Sarah, by the Midland Railway line, at an altitude of about 1800ft. Collections made at the end of November with a tow-net trailed slowly about six inches from the bottom, contained a large number of Glochidia. It is difficult to say whether the larvae were actually floating or were ejected by the parents as a result of the disturbance caused by the passage of the net through the water. It is probable that the latter is the explanation since, in such quiet water, organisms such as they with their relatively heavy shells would fairly readily sink after being ejected. Curtis and Lefevre (l.c., p. 98) have referred to the inability of Glochidia to propel themselves in spite of their flapping valves. They also (p. 101) point out that hooked Glochidia respond actively to tactile stimuli by closing up immediately on being touched. This applies equally well to the larvae of Diplodon.

Natural infections have been found in the young forms of the fishes, Galaxias brevipennis Günth. and Gobiomorphus gobioides Cuv. & Val. In the former case, the hosts were about 4.5 cm. long, and carried the parasites on the pectoral fins. In the latter case, the fish were about 1 cm. in length. The Glochidia had taken hold in various places, on the pectoral fins, on the upper lip clasping the