71 



it would appe ir that three important faunal changes can be traced in the 

 fossils of this Basal part of the Cambrian system. 



A conspectus of the several fossiliferous zones of the Etcheminian and Cold- 

 brook terranes of the Basal Cambrian in Cape Breton, with list of the 

 species zchich occur. 



In making this tabulation of the species and varieties of fossils in these 

 old Cambrian rocks it is necessary to use names in anticipation of the 

 descriptions further on in this report. Many of the species have already 

 been published in the Proceedings of the Royal Society of Canada, in the 

 Bulletin of the Natural History Society of New Brunswick (St. John, 

 N.B,), and in the Canadian Record of Science ; but the descriptions are 

 reproduced here as they have not appeared in any official report, and 

 because there is additional information to present with a number of the 

 species. 



The assises or zones are taken in their order from the oldest upward. 



COLDBROOK TERRANE, ASSISE "co." 



This is the only assise in which fossils have been found, in this terrane. 

 It consists of a body of gray shales about thirty feet thick, lying near the 

 middle of the terrane. The layer in which the fossils were found in chief Fossiliferous 

 abundance was a bed of compacted, slicken sided shale, from a pure gray Coldbrook 

 to a lavender gray in colour, and having a few grains of feldspar sand, volcanic 

 and scattered grains and pieces of calcium phosphate. The rock is harder 

 than the shales resembling it in the Etchminian terrane above, though it 

 is not any more silicious or sandy, and it lies between masses of volcanic 

 rock, chiefly ash beds and feisites. The presence of these shales in the 

 midst of the volcanics indicates a temporary cessation of volcanic activity; 

 and that the deposition of the fossiliferous bed occurred in comparatively 

 clear water is shown by the grains and lumps of calcium phosphate, with 

 which it is charged. 



Though thus peacefully interred, the valves of the Brachiopods were 

 afterward subjected to disturbing agencies by which they were twisted 

 and distorted, so that for many of the valves, the species, and even the 

 genera are unrecognizable. Hence it comes that the numbers given in 

 the list below do not by any means show the abundance of the fossils, as 

 many were not worth preserving. When the fossils happened to be 

 buried in calcium phosphate or filled with this mineral, the form was 

 preserved and it is mostly these that are listed. The smallness and the 



