Figures and Descriptions of Canadian Organic Remains. 303 



Brachiopod (Orthis Bomingeri, Barrande,) and one Pteropod 

 (Pugiunculus primus, Barrande,) but no Crinoids. 



"In Scandinavia the Primordial Zone has not yet yielded traces 

 of either Crinoids or Cystidese,but seventy-one species of trilobites, 

 and eight Brachiopods of the genera Lingula, Orbicula, Orthis and 

 Atrypa, have been discovered, with one or two graptolites and a 

 small orthoceratite, near the top. 



" In England the Lingula Flaga, which are regarded as the 

 equivalents of the Bohemian and Scandinavian deposits, have 

 furnished a very similar fauna of trilobites and rare mollusca, with 

 one or two graptolites ; but up to this date only a fragment of a 

 crinoidal column and no Cystideans. It is also to be observed, 

 that in none of these countries have any corals been detected in 

 these lowest fossiliferous strata. 



" In the upper half of the Lower Silurian, organic remains become 

 exceedingly abundant, and it is in this part of the geological series 

 that the Cystideae attain their greatest development, both in the 

 numbers of the species and of the individuals. This deposit i s 

 represented in England by the Llandeilo and Bala or Caradoc 

 groups of Murchison ; in Bohemia by the stage D. containing the 

 " second fauna" of Barrande ; in Scandinivia and Russia by the 

 Regions BC, C and D of Angelin, and the " Pleta" or Orthoceratite 

 limestone ; and in Canada by all the groups from the base of the 

 Calciferous Sandrock up to the top of the Hudson Riv.er group. 



" While these rocks were slowly being deposited, the Cystidese 

 literally covered the bottom of the ocean in dense swarms in certain 

 localities which were favorable to their existence, one generation 

 growing upon the remains of another, until thick beds were formed 

 In Russia, Norway and Sweden, Sir Roderick Murchison dis- 

 covered them in the Pleta limestone, which appears to be of the 

 age of the Chazy, Bridseye, Black River and Trenton lime- 

 stones, packed together like " bunches of enormous grapes ;" and 

 in Bohemia M. Barrande has found them equally abundant. He 

 says that the Crinoids and Star-fishes have left only insignificant 

 traces, but the Cystidese form entire beds of from one to two yards 

 in thickness. 



"In Canada they make their appearance rarely in the Calciferous 

 Sandrock, but in the Chazy and Trenton their remains are more 

 common, consisting however mostly of the detatched plates packed 

 together in thick strata. They are not very generally distributed, 

 but confined to certain localites. Throughout extensive regions 



