Spkigiit. — TJtc I'oxt-rilacidl Cliniafe of Canlerhvry . 411 



character of the huid Mollusca, and tlie others are mori' or k's.s botanical, 

 and luive to do witli the peat-bogs and the forests wliich formerly covered 

 wide tracts on the now treeless or almost treeless regions of Centrul Otago 

 and Canterbury. 



Land Mollusca. 



I am indebted to Mr. H. Suter for the following remarks on the land 

 Mollusca of the area. He says that they are certainly of a moist-climate 

 type, that the indigenous fauna is almost entirely confined to the bush, 

 and when this is destroyed or where there is no shelter from rotten logs 

 in moist situations, it disappears entirely. It must, therefore, have esta- 

 blished itself in tliis province when the climate was wetter. This argument 

 standing by itself is not convincing, as the establishment of this snail fauna 

 might date from a time anterior to the glaciation ; but taken with other 

 evidence it seems to strengthen the general conclusion that the climate 

 was once moister than it is now. 



Evidence from Peat-bogs. 



The evidence afforded by the peat-bogs of this country will, when they 

 have been properly studied, give data from which well-founded conclusions 

 can be drawn. At present their features are comparatively unknown, and 

 the statement still finds currency that they do not contain Sphagnum 

 (J. W. Harshberger : " Bogs, their Nature and Origin " — " The Plant 

 World," vol. 12, p. 36, 1909), although it really finds an important place 

 among peat-forming plants where the conditions do not allow of good drain- 

 age. In some cases where the drainage is bad, and again in other cases 

 where it is good, other plants contribute largely to the formation of the 

 peat. In these cases their ecological conditions are not thoroughly under- 

 stood at present, but they no doubt depend in some way on climate. Bogs 

 composed of Sphagnum, and also those formed otherwise, occur extensively 

 in both Canterbury and Otago, especially the latter. In the early days 

 of the settlement, peat was regularly cut from the bogs of the central district 

 of Otago and used as firing where wood was scarce. Extensive ])ogs were 

 found then on the tops of the flat-topped mountains, such as the Rock and 

 Pillar and Rough Ridge ; and Dr. Hilgendorf tells me that in the Waipori 

 district twenty-five years ago these bogs were full of totara logs, and other 

 logs lay exposed on the surface of the ground round the heads of gullies 

 in such a way that their distribution could only be explained by supposing 

 them to have been once bog-timber, which had been left stranded as the 

 bogs shrank. These bogs mentioned by Dr. Hilgendorf were in all pro- 

 bability not composed of Sphagnum, but there are others which do contain 

 wood and undoubtedly owe their origin to that moss. Dr. Hilgendorf's 

 statement that the bogs are shrinking in size is a very important one, and 

 if it could be absolutely substantiated it would prove that the climate has 

 undoubtedly changed ; but the effect of running stock over bog land tends 

 to consolidate it, and his statement, unless supported by other evidence, 

 would have to be taken with great care, seeing that sheep and cattle have 

 been pastured on these lands. I certainly think that such evidence exists. 

 It must be observed in this connection that the existence of Sphagnum 

 bogs in the dry region of Central Otago, with an average yearly rain- 

 fall of about 14 in., and with periods when it has fallen as low as Tin. 

 per annum, is very striking, since it has been proved that the growth 

 of Sphagnum depends chiefly on the water that it receives from the 



