Capt. F. W. Mutton — A Glacial Epoch in S. Hemisphere ? 581 



we must look with suspicion on all cosmical theories which attempt 

 to explain the cold of the Glacial Epoch. 



Mr. Croll's theory has found great favour because it was supposed 

 to rest on astronomical evidence, while in reality the astronomical 

 evidence is, if anything, slightly against it; and the theoiy is 

 founded on speculations in Meteorology, a science not even so well 

 understood as Geology. The theory of the change in the obliquity 

 of the ecliptic, advocated by Lieut. -Colonel Drayson, Mr. Belt, and 

 others, is simply a supposition which is altogether opposed by astro- 

 nomy. 1 For if the position of the ecliptic has ever changed as much 

 as has been supposed, it is evident that astronomers must be wrong in 

 attributing the present change in the obliquity to the joint attraction 

 of the planets ; and in my opinion it is premature to call in cosmical 

 theories, founded on conjecture, to explain the cold of the Glacial 

 Epoch, until we are compelled to do so by the absolute proof of its 

 universality. 2 



But at present there is no proof of a Glacial Epoch in the Southern 

 Hemisphere, and all the evidence that can be adduced on the subject 

 appears to me to negative such a supposition. There are only three 

 countries where we can expect to obtain proof or disproof of the 

 former existence of a Glacial Epoch in the Southern Hemisphere, 

 viz. South America, New Zealand, Tasmania and Australia ; and 

 I have placed the names in the order of their relative import- 

 ance with regard to this question. I will begin with New Zealand, 

 which is the only one of the three on which I can offer any original 

 observations. 



New Zealand extends over 13 degrees of latitude from 34° S. to 

 47° S. and the difference between the mean annual temperatures of 

 the two extremities is rather more than 10° Fahr. Having resided 

 at Auckland in the north, at Wellington in the centre, and at 

 Dunedin in the south, I can, from my own observations, state that a 

 considerable difference exists in the molluscan faunas of all these 

 three localities. It would, perhaps, be more correct to say that the 

 northern and southern extremities of New Zealand have each their 

 own fauna (which commingle in Cook Straits), with, however, a pre- 

 ponderance of northern forms. This difference in the faunas is 

 greater than would appear by mere lists, for many species which are 

 abundant in the north are extremely rare in the south, and some 

 species that are abundant in the south are very rare in the north. I 

 do not intend here to go into details on this subject ; I only wish to 

 point out that New Zealand extends over a sufficient number of 

 degrees of latitude, and has a sufficiently different fauna at its 



1 The theory referred to by Capt. Hutton is indeed opposed to the views of some 

 astronomers, but not necessarily therefore to Astronomy. — Edit. Geol. Mag. 



2 A more serious difficulty for Geologists has arisen than that of explaining the 

 cold of the Glacial epoch ; namely, to explain the warm-temperate and even sub- 

 tropical heat of the Earlier Tertiary periods in high northern latitudes. Such 

 changes are not "founded on conjecture." See Prof. Nordenskiold's article in the 

 November Number of the Geol. Mag. p . 525. See also Address to the Geologists' 

 Association, by H. Woodward, F.K.S., Nov. 6th, 1874, Proc. Geol. Assoc. 1875, 

 vol. iv Edit. Geol. Mag. 



