﻿Notice of Memoirs— A. W. Waters. 219 



we find further evidence that the ancient ganoids formed the parent 

 stock from which the succeeding fishes, amphibians, and reptiles 

 Lave diverged. In some sauroid Devonian fishes the position and 

 structure of the teeth foreshadow those of the Labyrinthodont reptiles, 

 in others the throat is protected by gular plates, a fashion retained 

 in the Carboniferous amphibia. Again, in some species the scales 

 are surface pitted, like the scutes of Crocodiles. While, in the noto- 

 chordal weak-limbed amphibians of the Coal-measures, with minute 

 body scales, and partly osseous skulls, we cannot fail to recognize 

 structural peculiarities now found in the swamp-dwelling mud-fishes. 

 Thus in the anomalous " scaled sirens," we have the " persistent 

 type " of an ancient group of fishes, in which now, as in the old 

 time, the piscine and amphibian characters are so united as to com- 

 pletely efface the line of demarcation between the orders, and effectu- 

 ally link the fishes to the reptiles. 



Pkoceedings of the Manchester Literary and Philosophical 

 Society, vol. xvi. No. 10, p. 171. Session 1876-77.— Ordinary 

 Meeting, March 6, 1877. 



A PAPER was read by Mr. Arthur Wm. Waters, F.G.S., entitled 

 "Inquiries concerning a Change of Position of the Earth's 

 Axis." The author stated that the cause of the greater warmth in 

 high latitudes during the Tertiary period had not, in the opinion of 

 many, yet received any satisfactory solution. 



The Arctic Miocene Flora was considered. 356 Miocene species 

 of plants have already been determined from latitude 70-77 N. in 

 Spitzbergen and Greenland, and include Tnxodimn (swamp cypress 

 of Texas), Sequoia, birch, lime, oak, beech, plane, and even mag- 

 nolia ; so that Prof. Heer, by comparison of the localities of these, 

 says that the temperature must have been 30° F. warmer than at 

 present. Fossil floras of the Cretaceous, Jurassic, and Carboniferous 

 periods have been discovered within the arctic circle. Most of these 

 plants are unable to resist severe cold, besides requiring a warm 

 summer, and it seems difiicult to accept the fact of their flowei'ing 

 and ripening their seeds, where the winters are so long and the 

 summers so short, and, apart from the lower temperature, where the 

 amount of light is so much diminished. 



Several theories have been brought forward to explain the cold of 

 the Glacial Period, the generally received one being that of Mr. 

 Croll, that it was brought about indirectly from an increase in the 

 eccentricity of the earth's orbit, modified by the obliquity of the 

 ecliptic. In the longer and colder winters more snow fell, which the 

 summer could not melt awaj^ so that the earth now covered gets 

 little of the warmth of the sun. As this explanation has not always 

 been thought quite satisfactory with regard to the greater warmth, 

 the change of the position of the earth's axis has from time to time 

 been suggested on various grounds. 



