170 THE CANADIAN NATURALIST. [Vol. viii. 



The Laurentian apatite pretty constantly contains a small per- 

 centage of calcium fluoride ; and this salt also occurs in bones, 

 more especially in certain fossil bones. This may in both cases be 

 a chemical accident ; but it supplies an additional coincidence* 



In the lowest portions of the Lower Laurentian no organic re- 

 mains have yet been detected ; aud these beds are also poor in 

 phosphates. The horizon of special prevalence of Eozoon is the 

 Grenville band of limestone, which, according to Sir William 

 Logan's sections, is about 11,500 feet above the fundamental 

 gneiss. It appears, from recent observations of Mr. Veunor and 

 Mr. W. T. Morris, that the bed holding the Burgess Eozoon is 

 on the same horizon with the limestone of Grenville. The phos- 

 phates are most abundant in the beds overlying this band. This 

 gives a further presumption that the collection and separation of 

 the apatite is due to some organic agency, and may indicate that 

 animals having phosphatic skeletons first became abundant after 

 the sea-bottom had been largely occupied by Eozoon. 



I would not attach too great value to the above considera- 

 tions; but, taken together, and in connection with the occurrence 

 of apatite in the Cambrian and Silurian, they seem to afford at 

 least a probability that the separation of the Laurentian phosphate 

 from the sea-water, and its accumulation in particular beds, may 

 have been due to the agency of marine life. Positive proof of this 

 can be obtained only "by the recognition of organic form and 

 structure ; and for this we can scarcely hope, unless we should be 

 so fortunate as to find some portion of the Lower Laurentian 

 series in a less altered condition than that in which it occurs in 

 the apatite districts of Canada. Should such structures be found, 

 however, it is not improbable that they may belong to forms of 

 life almost as much lower than the Linguloe and Trilobites of 

 the Cambrian as these are inferior to the fishes and reptiles of 

 the Me.-ozoic. — From the Quarterly Journal of the Geological 

 Society. 



