132 Reports and Proceedings — 



able sediments to that extent are found over those parts of the areas 

 first submerged, and which remained undisturbed. That volcanic 

 action was chiefly confined to parts of the regions which became 

 first submerged. That the immediate cause of these outbursts was 

 the weakness of the pre-Cambrian crust at those parts, from the 

 great depression that had taken place, it being too thin there 

 to resist the pressure from within, and to bear the weight of the 

 superincumbent mass of soft sediment. 



5. That the seat of volcanic action at this time was at a depth of 

 probably not less than 25 miles, as sediments which were depressed 

 to a depth of from 9 to 10 miles do not indicate that they had been 

 subjected to the effect of any great amount of heat, and are free 

 from metamorphism. 



6. That the climate at the early part of Palaeozoic time was one 

 of very considerable, if not extreme cold, and that it became gra- 

 dually milder after each period of depression. That towards the 

 close of the Palaeozoic epoch, in consequence of the elevation of very 

 large areas, and to a great height, the climate became again more 

 rigorous in character. 



7. That the various changes which took place over the northern 

 latitudes during Laurentian and Palaeozoic times allowed marine 

 and land life to develope and progress in those areas at interrupted 

 periods only ; consequently most of the progressive changes in the 

 life had to take place in more equatorial areas, where the sea-bottom 

 was less disturbed, and where the temperature was more equable. 

 Any imperfection therefore in the Palaeontological record belonging 

 to these early times should be attributed to these and like circum- 

 stances ; for wherever an approach to a complete record of any part 

 of the chain is preserved to us, the evidence points unmistakably to 

 an order of development, through a process of evolution from lower 

 to higher grades of life. 



II.— January 19, 1876. — John Evans, Esq., E.E.S., President, in 

 the Chair. — The following communications were read : — 



1. '' On some Unicellular Alg£e parasitic within Silurian and 

 Tertiary Corals, with a notice of their presence in Calceola sanda- 

 lina and other Fossils." By Prof. P. Martin Duncan, F.R.S., 

 V.P.G.S., etc. 



After noticing the works of Quekett, Rose, Wedl, and Kolliker, 

 which refer to the existence of minute parasitic borings in recent 

 corals, recent shells, and a few fossil mollusca, the author describes 

 the ap2:)earance presented by a great system of branching canals of 

 about 0-003 millim. in diameter, in a Thamnastrsean from the 

 Lower Cainozoic of Tasmania. He then proceeds to examine the 

 corresponding tubes in Goniophyllum pyramidale from the Upper 

 Silurian formation. In sections of that Coral one set of tubes runs 

 far into the hard structure ; these are straight, cylindrical, and con- 

 tain the remains of vegetable matter. Neither these tubes, nor any 

 others of the same parasite, have a proper wall; they are simply 

 excavations, the filiform alga replacing the organic and calcareous 

 matter abstracted. In some places the dark carbonaceous matter is 



