cascades from the source of the largest springs to the bottom where its waters flow into the creek. As the water spreads out in several directions after issuing from the earth there are different series of these basins, and altogether they would cover about a quarter of an acre. Where there is water on the rims it is quite shallow, but a considerable part of most of them is exposed. A few inches from the edge the water deepens to 6 in. or 8 in. Covering the bottoms of these pools or basins, which vary in area from less than a square foot to several square yards, there is a slimy vegetable growth of dark-green colour of varying thickness. While on a visit to these springs last March I noticed great numbers of small flies hovering about the pools or on the silica at their edges. They were really in millions, some of the dry patches of silica being covered by them to a depth of an inch or more. Their size was about half that of the common house-fly. In shape they were something similar, but more slender and graceful, and of a dark colour, almost black. Their power of flight was feeble. I asked a resident of the locality if they appeared in the autumn only, but he assured me that they were there all the year, and that in the spring-time numbers of native birds gathered about the springs to feed upon them. It occurred to me that they might breed in the hot water, and so I examined the organic matter at the bottom of the basins. It was alive with larvæ about one-half as large as that of the blow-fly, of a dark greyish-green colour, shaped curiously like a shark with its double-lobed tail. In still pools this slime could be seen all in motion, so numerous were these larvæ. The green matter was evidently their food, and supported them generously, judging by their numbers. On the surface of the water a great many pupa-shells were floating. These shells drifted to the lips of the basins, and in a great many places, becoming entangled, they formed small obstructions across the little depressions through which the water flowed. As silication proceeds rapidly in most of these springs, it is obvious that these rafts of shells, being cemented together and to the basin-edges by the silica, will in time raise the level of the water, compelling it to find an exit elsewhere, and this in turn will get blocked too. This may afford an explanation of the remarkably level nature of the walls of these small reservoirs. I broke off a piece of the top of one of these dams, and the outlines of numerous shells imbedded in the silica were clearly visible. I regret very much that my visit. which was limited to about an hour, prevented me from making further observations. Some specimens of the fly were sent by Mr. Hudson