520 Proceedings. 



never could have made them in the first instance ; and their great 

 antiquity was proved by the manner in which tliey led up to both sides 

 of great rents that had shattered the mountain-plateau, arising from that 

 constant denudation of its flanks which was still in progress. The accurate 

 study of such areas would afford a splendid holiday outing for young New 

 Zealand naturalists. With respect to this particular locality, a good 

 beginning had been made by Llr. Mclvay in its geology, Mr. Cheeseman 

 in its botany ; and now Mr. Hudson had in this paper shown that its 

 insect-life was full of food for study. The mystery referred to of the blue- 

 bottle fly occurring at high altitudes had yet to be solved ; the speaker 

 had seen them issuing in thousands from a crevasse in a glacier at 

 8,000ft. altitude. 



Mr. McKay said that on the east edge of the table-land there was a 

 tract of country honeycombed with caves, which should afford a large 

 field to those in search of such forms as had been described by Mr. 

 Hudson ; but care would be required in venturing into the deeper recesses 

 of this cavernous formation, since, if once the way were lost, escape would 

 be almost impossible. 



Mr. Park had seen the flesh-fly in great numljers at altitudes of 

 5,000ft. to 6,000ft. 



Mr. Hudson, in reply, said that, with reference to the remarks made 

 by Sir James Hector and others on the occurrence of the flesh-fly at 

 great elevations, on glaciers, &c., he could only explain the circumstance 

 as instances of insect-migrations. The blue-bottle fly, owing to its 

 longevity (many individuals frequently living fully nine months in the 

 imago state), would be especially able to undertake such journeys ; and 

 the fact of its doing so in past times might be inferred from the present 

 universal distribution of the species of flesh-flies throughout New Zea- 

 land. 



In reply to questions by Mr. ]\Iaskell as to the universal occurrence 

 of dark-coloured insects at high altitudes and in the arctic regions, the 

 author stated that all collections which had yet been made either on the 

 tops of mountain-ranges or in the northern arctic or sub-arctic regions 

 exhibited an invariable tendency to melanism : that it was considered to 

 be the .result of natural selection winnowing out the lighter forms, which 

 were unable to stand in the struggle with the cold, and that those whose 

 colouring enabled them to absorb the transient heat had alone survived. 

 The white coloration of the warm-blooded vertebrates in the arctic regions 

 was advantageous to them in enabling them to retain their internal heat, 

 and the dark coloration to the Inscct(P in enabling them to absorb the 

 external heat. 



2. " On certain Eare Minerals associated with the Tin-ore 

 of Stewart Island," by William Skey, Analyst, Geological 

 Survey. {Transactions, p. 415.) 



3. " Notes on the Minerals from Stewart Island described 

 by Mr. Skey," by Alexander McKay, F.G.S. {Transactions, 

 p. 415.) 



Sir James Hector said that tin had been found in small quantities in 

 various parts of New Zealand, but Port Pegasus was quite a new 

 though not an unexpected locality. He fully expected the same class 

 of mineralized rocks to be found along the west side of Te Anau Lake. 

 The variety of rare mineral specimens which had been collected by Mr. 

 McKay, and analysed and identified by Mr. Skey, was very remarkable and 

 especially promising. Giving a description of the range of the formation, 

 by reference to a large geological map, Sir J. Hector pointed out that 

 the mineral belt, which was characterized by highly-differentiated and 



