454 Mr. R. Kiikpatrick on the Structure of 



time) lie distinctly records his opinion that tliey are Forami- 

 iiifera, and even gives fairly good reasons for his faith; but 

 he (ailed to convince his successors. 



Note 2. — Recently I have examined a tliick section of a 

 specimen in my own possession labelled " Favosites, Wen- 

 lock." I find that it is certainly not a Monticiiliporoid. 

 Accordingly I withdraw the statement I made to the efEect 

 that the genus Favosiies comes within the Monticuli2)ora 

 group (i. e. siliceous sponges with supplementary calcareous 

 skeletons). 



Note 3.— In the ' Annals ' for Sept. 1912 I also stated 

 that Eozooa was allied to Beatricea. At that time I held 

 the same views on Eozoon as Carpenter, and regarded the 

 spaces formed by the secondary skeleton as huge vesicular 

 chambers. Of course a space bounded by secondary skeleton 

 and containing a rouleau of Nunimulitid shells is in no way 

 to be compared with one of the chambers of Beatricea with 

 its thin curved roof of primary skeleton. 



Note 4. — Both Stromatoporoids and Eozoon have laminated 

 structure, and the weathered edges show the layers, which, 

 however, have an entirely different origin. The edges of 

 Stromatoporoids are those of horizontal coils of spiral 

 chambers, but the edges seen in Eozoon are mainly those of 

 the supplementary skeleton. The structures in Eozoon 

 really corresponding to the edges of the layers of Stromato- 

 poroids are the margins of the upright-standing Nummulitid 

 shells arranged in horizontal rouleaux. 



Note 5. — Eozoon must liave grown in shallow seas and 

 may have formed fringing reefs to continents. At the 

 present day coral-reefs are distributed within the tropic and 

 sub-tropic belt ; but in the earliest times probably the waters 

 of the globe were practically isothermal, just as in a kettle of 

 water over the tire, the bottom of the kettle representing the 

 thin consolidated crust ot the earth. When the internal heat 

 was withdrawn owing to thickening of the crust, the outside 

 meteorological influences would set up the various isothermal 

 zones at present existing. 



Seeing that we now know definitely that Archaean lime- 

 stones were of organic origin, it does not seem unreasonable 

 to assume that the bands of gneiss below and above them 



