Correspondence — Rev. W. B. Clarke. 383 



The reason why we have so little snow, and consequently so little ice, 

 in temperate regions, is not, as Mr. Murphy seems to suppose, that 

 the heat of summer melts it all, but that there is so little to 

 melt. And the reason why we have so little to melt is that, owing 

 to the warmth of our winters, we have generally rain instead of 

 snow. But if you increase the eccentricity very much, and place 

 the winter in perihelion, we should probably have no snow whatever, 

 and it would then, in so far as glaciation is concerned, matter very- 

 little what sort of summer we had. 



But it is not correct to say that the perihelion summer of the 

 glacial epoch must have been hot. There are physical reasons 

 which go to prove that, notwithstanding the nearness of the sun at 

 that season, the temperature would seldom if ever rise much above 

 the freezing point. See Philosophical Magazine for August, 1864, 

 pp. 134, 135 ; February, 1867, pp. 125, 126. James Croll. 



Edinburgh, July 8th, 1869. 



DINOENIS AN AUSTRALIAN GENUS. 



Sir, — It will be interesting to your readers to know, that evidence 

 has at length been discovered of the former existence in Continental 

 Australia of birds of the Pleistocene New Zealand genus Dinornis. 



A short time since a well was dug in that part of the Peak Downs 

 in Queensland (about lat. 22° 40' S.) between Lord's Table Mountain 

 and the heads of Theresa Creek, near the track from Clermont to 

 Broad Sound. 



The well passed through 30 feet of black trappean alluvial soil, 

 so common in Australia, which rested on 150 feet of drift pebbles 

 and boulders, on one of which (at that depth) rested a short thick 

 femur, so filled in with mineral matter (calc spar and iron pyrites) 

 as to give the internal structure more the appearance of a reptilian 

 than an ornithic bone. I have never yet seen any bone in Australia 

 so much mineralised and yet retaining its distinctive osseous fea- 

 tures. When placed in my hands it had been already broken in two, 

 just as a bird's bone would be likely to break. But besides this 

 there are two crushed-in fractures of ancient date, which have 

 broken in the surface of the bone, and if not made in the life time 

 of the bird, were probably made by the violence of the heavy drift 

 in which it was found. 



I had an opportunity of comparing it hastily at the Australian 

 Museum in company of Mr. Gerard Kreflft, our able Curator, and 

 was convinced of its being a bird bone allied to Dinornis, to which 

 opinion I was afterwards led by reference to the writings of Pro- 

 fessor Ov/en. Since then Mr. Krefft has compared it with a collec- 

 tion sent over from New Zealand by Dr. Haast, and has been enabled 

 to determine it to be a bone belonging to Dinornis. 



I take advantage of the departure of the mail to-morrow to an- 

 nounce this fact, waiting for a further account of the specimen fi-om 

 Mr. Krefft. 



The Peak Downs were discovered by Leichhardt in his famous 

 expedition to Port Essington in 1845. 



