after which stage the pent-up fires burst forth in the stupendous form of Ruapehu, and when the latter in its turn became extinct, Tongariro, with its minor system of volcanic cones, sprang into existence. [Illustration: TERRACE FORMATION AND HOT SPRINGS. (_Valley of the Waikato._)] I am not aware whether this theory of the crater basin of Lake Taupo is a new or an old one, and I only endeavour to exemplify it as it presented itself to my mind, after a careful examination of the country for many miles around the lake, and from data gained during my ascent of the highest mountains of this great volcanic centre. I may, however, likewise point out that the Taupo natives still have a well authenticated tradition, which would seem to show that even during the history of the race upon the island, the lake basin was at one period considerably higher than it is at the present day. But, beyond the above fact to support this theory, it is well known that the formation of lakes in extinct craters is common throughout the volcanic regions of the island. Lake Takapuna, near Auckland, may be taken as a notable instance. The blue lake at Wairakei, near Lake Taupo, is situated in a depressed crater, and Rotokawa, a little further to the east, is of the same formation. Lake Rotoaira, south of Taupo lake, is nothing more than a depressed crater, while there are no less than four lakes on the Tongariro mountains formed in the same way. There is likewise a lake formed by a crater on the summit of Ruapehu, while the two lakes which I discovered to the south-west of that mountain, and named respectively Rangitauaiti and Rangitauanui, were nothing more than depressed craters filled with water from subterranean springs.