

78 PROC. COTTESWOLD CLUB vol. xin. (2) 



is a mere mineral mimicry of an organic structure. It 

 has also been contended, it is still contended by some 

 authorities, that the occurrence of limestones in these 

 ancient rocks is a proof of the agency of living beings. I 

 have elsewhere* given reasons for treating this opinion 

 with extreme scepticism, and in the same paper I have 

 pointed out the insufficiency of the arguments based upon 

 the presence of iron ores, graphite, apatite, and metallic 

 sulphides. I do not consider that the chemical evidence 

 for the existence of animals or plants in the Lower 

 Archaean formations is of any decisive value. I will go 

 even further. I hold that these rocks never can furnish 

 any evidence for the existence of living beings. For 

 these gneisses and schists are of plutonic origin. They 

 are igneous masses, formed at great depths in the earth's 

 crusts, under enormous pressures, and at temperatures 

 which sometimes caused absolute fusion. This con- 

 clusion has been proved for the Malvernian masses of 

 Malvern and the Highlands ; and American geologists are 

 applying the same interpretation to most of the Laurentian 

 rocks of the Western Continent. 



The older Archaean formations being thus excluded 

 from our purview, we turn to the newer rock-groups. I 

 will first notice the evidence furnished by foreign localities. 



In Southern Brittany is found a graphitic quartzite 

 which has yielded numerous minute fossils. The rock 

 forms part of the series of Saint-L6, which is the probable 

 equivalent of our Pebidian, but at least is certainly Pre- 

 Cambrian. The fossils have been referred by some of 

 the highest authorities to the Radiolaria, unicellular 

 gelatinous bodies enclosed in a siliceous test, which is 

 usually spherical in form, but sometimes ellipsoidal, and 

 often bell-shaped. The w-all of the test is perforated, but 



* Proceedings of the Liverpool Geological Society, 1896-97, p. 98. 



