The Principles of Palaeontology. 187 



cated evolution, as is proved by the embrjogeny of the existent 

 forms, some of which are almost identical with the Cambrian 

 species. "The well authenticated animal discovered in one of 

 the oldest layers is justly^ ranked as a Lingulid, Lingulella 

 primcBva.'*' At a yet more remote epoch are found traces which 

 have been attributed to the Annelids. I do not speak at present 

 of the bodies called Eozoon^ which probably have not an organic 

 origin. 



It is then very evident that we do not really know the true 

 primordial fauna. That which characterizes the lowest Cambrian 

 has, it is true, an expression of decided simplicity, for no Mollusks 

 are found there except shells of doubtful relationship (TAecti^), 

 neither are Echinoderms, nor Corals nor Yertebrates ; these forms 

 which appear suddenly and without apparent preparation, in the 

 upper Cambrian or the Ordovician, may perhaps have existed in the 

 lower Cambrian, but they were then destitute of the hard parts 

 (shell, test or skeleton), which would prove their state of inferi- 

 ority, or they existed in regions which possessed a different facies 

 not yet discovered. 



Origin of life. Precambrian deposits. — We know nothing 

 whatever in regard to the origin of the Cambrian fauna, found 

 to be almost identical in every part of the globe. 



The Cambrian deposits nevertheless are not the oldest of the 

 sedimentary formations. At a lower horizon there exist, in 

 diverse regions, layers which have been formed in the sea ; such 

 are the enormous deposits of Canada formed by the Laurentian 

 and Huronian stages, which together are more than 20 kilometres 

 in thickness. The Precambrian terrane of the coiintry of Gallee, 

 also very thick, is found under the Lingula flags. In Canada, in 

 the Laurentian period, besides the famous Eozoon, Dawson found 

 carboniferous matter and tubules which he attributed to the worms. 

 The presence of thick masses of bitumen and graphite in the 

 Precambrian beds has a considerable importance. Among the 

 chemical phenomena which living nature presents, the only ones 



♦ [See previous foot note. Lingulella is always a distinctly more primitive type than Lingula, as 

 shown not only in Its ontogeny, but also in the close relations of its actual characters to Obolella. 

 Beecher's determination of the radicle of the Brachiopod shell, Paterina, in the Cambrian, and its 

 close relation to such pre-eminent members of this fauna as Obolus, Obolella and Lingulella indicate 

 that the evolution of these forms may have been more simple and direct than the author here 

 supposes.— Ed.] 



