Frof. Garwood — Calcareous Algce. 491 



In the Archaean rocks no undoubted remains of Calcareous Algae have 

 yet, so far as I am aware, been recorded, but Sederholm considers that 

 'certain small nodules in the Archaean schists of Finland may represent 

 vegetable remains. I may also perhaps here refer to some curious 

 oolitic structures which I met with in Spitzbergen in 1896 when 

 examining the rocks of Hornsund Bay. These oolites occur on the 

 south side of the bay, and are closely connected with massive siliceous 

 rocks which may represent old quartzites. The whole series is much 

 altered, and detailed structure cannot now be made out. The rocks 

 occur apparently stratigraphically helow the massif of the Hornsund 

 Tinde, and may belong either to the Archaean or the base of the 

 Heckla Hook Series. As, however, similar rocks have not been 

 recorded from the type district of Heckla Hook, they may be referred 

 provisionally to the Algonkian, and may represent the quartzites and 

 earthy limestone of the Jotnian Series of Scandinavia. They are 

 mentioned here in connexion with Mr. Wethered's view that oolites 

 are essentially associated with the growth of Girvanella. 



CAMBRIAIir. 



Passing on to the Palaeozoic rocks, we find in the Cambrian deposits 

 hut few indications that Calcareous Algae played any considerable 

 part in their formation. 



This is no doubt due, to some extent, to the conditions under which 

 these deposits accumulated in the classical localities where true 

 calcareous deposits are typically absent. In the Durness Limestone, 

 however, where considerable masses of dolomites occur, the conditions 

 would appear at first sight to have heen more suitable for the growth 

 of these organisms ; but even here the slow rate of accumulation and 

 the large amount of contemporaneous solution may have militated 

 against their preservation. At the same time, it is possible that 

 a systematic search in the calcareous facies of the Cambrian rocks in 

 the North of Europe and America may result in the discovery of the 

 remains of some members of this group,. That there is ground for 

 this suggestion is shown by recent work in the Antarctic Continent. 

 ' Professor Edgeworth David and Mr. R. E. Priestley have discovered 

 among the rocks on the north-west side of the Beardmore Glacier 

 ■dark-grey and pinkish-grey limestone containing the remains of 

 Archaeocyathinae, Trilobites, and sponge spicules, together with 

 abundant remains of a small calcareous alga referred provisionally to 

 Solenopora. From the photographs exhibited by Professor David on 

 the occasion of his lecture (February 8, 1911) to the Geological 

 Society, I have little doubt that this reference is correct. 



A further occurrence of Solenopora is also reported from fragments 

 of a limestone breccia collected by the Southern party from the western 

 lateral moraine of the same glacier. Speaking of the fauna discovered 

 in this limestone Professor David remarks : " The whole assemhlage is 

 so closely analogous with that found in the Lower Cambrian of South 

 Australia as to leave no doubt as to the geological age of the lime- 

 stones from which these fragments are derived." ^ This discovery, 

 ^ Eleventh Internat. Geol. Congress Eeport, 1910, p. 775. 



