height of the snow line is the position of the line of mean annual temperature of 32° F., its absolute height at any particular point depends on many local causes, as well as on the general one of the decrease in temperature in ascending from the sea level. We are not, however, without data for ascertaining the average height of the snow line with sufficient accuracy for our present purpose. Pembroke Peak, near Milford Sound, is 6,710 feet high, and not only is it always covered with snow, but a small glacier comes down from it towards Harrison Cove. The quantity of snow on this mountain is, no doubt, owing to local causes, and it would be incorrect to take the snow line in Otago at so low a level as this would give. On the other hand 8,000 feet would be too high an estimate, for there is no mountain in Otago, whatever be its aspect or steepness, that attains to this altitude without having snow upon it in places all the year round, and I think that 7,000 feet might be taken as the average height of the snow line in Otago.

In the North Island we have in Ruapehu an excellent standard for estimating the height of the snow line there. This mountain is 9,195 feet high, and its summit is always snow-clad, consequently we cannot take the height of the snow line in the centre of the North Island at more than 9,000 feet. If now, taking these two as fixed points, we calculate the altitude of the snow line at those places, where it is necessary that we should know it in order to follow out the argument, we find that at Mount Franklin, in the Nelson province, it would be 8,000 feet; at Wellington 8,300 feet, and at Auckland, 10,000 feet, which is rather higher than the snow line in corresponding latitudes in the Andes.

The next point is to try to estimate the amount of elevation that would be necessary to bring back the glaciers to their former size. Mr. A. D. Dobson, after a careful examination of the Nelson district, says ^*:—“During the period the line of perpetual snow must have been very much lower down the mountains than it is at present. I should be inclined to think that it was about on a level, which is now only about 4,500 feet above the sea.” This, if we take 8,000 feet as the present height of the snow line, would require an elevation of 3,500 feet to bring about. In my former paper on this subject I said that “an elevation of 2,000 to 3,000 feet would be sufficient to account for all the phenomena;” ^† and Mr. W. Travers says in his paper that it would require an elevation of not less than 4,000 to 5,000 feet. ^‡ But Mr. Travers estimates the height of the snow line in Nelson at 9,000 feet; and, if we reduce this to my estimate of 8,000 feet, it will be necessary to deduct 1,000 feet from the elevation he requires. This will

bring it to between 3,000 and 4,000 feet, which is about the amount estimated in a different way by Mr. Dobson. This estimate I am willing to adopt, for, since my examination of the province of Otago, I think it more correct than my previous one.

Now the mean annual temperature of the following places is as under:—

And, if we take the mean annual temperature of the snow line to be 32° F., this will give a decrease of 1° F., in temperature for every 363 feet in altitude at Auckland, 353 feet at Wellington, and 374 feet at Dunedin. I will therefore adopt a mean of 363 feet for New Zealand.

From this it follows that a reduction of the temperature of Wellington to that of Dunedin would be equivalent to an elevation of 1742 feet, a reduction of the temperature of Auckland to that of Dunedin would be equivalent to an elevation of 3,194 feet, while the reduction of the temperature of Monganui to that of Invercargill would be equivalent to an elevation of 3,357 feet. So that in order to bring back the former extension of the glaciers, by change of climate alone, the mean temperature at Monganui would have to be reduced below the present mean temperature of Invercargill—that is to say, the whole climate of New Zealand would have to be reduced by more than 10° F.

Now in the pleistocene beds of Wanganui, Motarau, and Oamaru we find the following species of recent shells, none of which are as yet known to extend as far south as the coasts of Otago.^*

On the other hand, Pecten radiatus, which at present has only been found at Stewart Island, occurs fossil in the Wanganui pleistocene beds. There is, however, a considerable balance of evidence in favour of the climate of Cook Strait having been, in pleistocene times, warmer than the present climate of Otago.

In the newer pliocene beds of Shakespeare Cliff, Wanganui, we find, in addition to twelve of the foregoing, the following additional species:—

• Murex zealandicus

• Fusus pensum.

• " australis.

• " mandarinus.

• " dilatatus.

• " littorinoides.

• Pleurotoma novœ zealandiœ.

• Pleurotoma buchanani.

• Crypta costata.

• " profunda.

• Buccinulus kirki.

• " alba.

• Dosinia lambata.

all of which live north of Cook Strait, but none of them are known from Otago. However, in the same beds, Pleurotoma lœvis and Pecten radiatus also occur, which at present are only know to live in Foveaux Strait. On the whole then the evidence is against the idea that a colder climate formerly obtained in New Zealand.

But this is not all, for the following species, none of which are now found alive in Otago, have survived from the miocene period, as they occur in upper miocene rocks (Pareora formation) between Cook Strait and Dunedin.

• Fusus australis.

• " mandarinus.

• " dilatatus.

• " nodosus, var. β.

• Pleurotoma buchanani.

• Voluta gracilis.

• Struthiolaria scutulata.

• Turritella vittata.

• Crypta costata.

• " contorta.

• " profunda.

• Cylichna striata.

• Mactra inflata.

• Zenatia acinaces.

• Venus zealandica.

• Mysia zealandica.

On the other hand, there is in the Museum a Cominella from the miocene beds of Waikari in Canterbury, which appears to be identical with an undescribed species from Campbell Island.

As none of the shells in these lists can now live on the Otago coasts, we have every reason to suppose that if the sea at Monganui had ever been reduced to the present temperature of that at Dunedin, they could not have lived there either, and consequently they would have become extinct in New Zealand.

Now, as 27 out of these 36 shells are littoral species found only in New Zealand, we should have to suppose, if the extension of the glaciers was