[Read before the Otago Institute, 1st October, 1912.]
This paper deals with twenty-two species of Rotifera which have not so far been reported as having been found in the Dominion. It is the result of four years' pretty constant searching of between two and three hundred ponds and creeks, chiefly in North Otago, by myself and half a dozen other willing helpers. During the course of this period I have mounted some two thousand slides of pond-life, adopting Mr. Rousselet's formalin method in the majority of cases, and always with the best results so far as the preservation of the specimens was concerned; and my slides of Rotifera mounted four years ago are as good to-day as they were when first rung. I have, of course, come across many other species, such as Floscularia ornata, Melicerta ringens, Rotifer vulgaris, Hydatina senta, &c., round about Oamaru, but as these have already been recorded in the Trans. N.Z. Inst. I have not referred to them.
North Otago appears to be particularly favourable to Rotifers, and it is interesting to note that most of the species are more numerous in the late winter months than at any other time of the year; indeed, they almost entirely disappear in autumn and early winter. This is, I believe, just the reverse of what takes place in Europe, and is probably due to the fact that most of our ponds and streams dry up towards the end of summer. Low temperatures seem to have very little effect on them, and it will be remembered that Mr. James Murray, of the “Nimrod” Expedition, found living Rotifers frozen under 20 ft. of ice in a small lake at Cape Royds, South Victoria Land. It is somewhat remarkable that there should be such a dearth of new species in the locality under consideration. One might imagine that in New Zealand especially there would be some departure from the stereotyped forms of the Northern Hemisphere, but this has not proved the case in our district at any rate, and it may be attributed to the well-known fact that Rotifers and their eggs may be conveyed long distances by wind and the feathers of migratory birds.
For assistance in procuring specimens I wish to thank Miss Gore and Miss Lory, of Oamaru; Mr. G. Howes, of Dunedin; and my assistant, Arthur Willetts.