No. 3.] DAWSON — PHOSPHATES OF CANADA. 1G9 



while the containing strata are highly metamorphosed ; and this 

 appears to be its general condition wherever it has been examined. 

 Numerous slices of the more compact apatite of the beds have 

 been prepared by Mr. Weston, of the Geological Survey; but, 

 as might be expected, they show no trace oY organic structure. 

 All direct evidence for the organic origin of this substance is 

 therefore still wanting. There are. however, certain considera- 

 tions, based on its mode of occurrence, which may be considered 

 to afford some indirect testimony. 



If, with Hunt, we regard the iron ores of the Laurcntian as 

 organic in origin, the apatite which occurs in them may reason- 

 ably be supposed to be of the same character with the phosphatic 

 matter which contaminates the fossiliferous iron ores of the 

 Silurian and Devonian, and which is manifestly derived from the 

 included organic remains. 



If we consider the evidence of Eozoon sufficient to establish 

 the organic origin, in part at least, of the Laurentian limestones, 

 we may suppose the disseminated crystals of apatite to represent 

 coprolitic masses or the debris of phosphatic shells and crusts, 

 the structure of which may have been obliterated by concretion- 

 ary action and metamorphism. 



Such Silurian beds of compact and concretionary apatite 

 (without structure, yet manifestly of organic origin) as that 

 described by Mr. Davies in the ' Journal ' of this Society, may be 

 taken as fair representatives of the bedded apatite of the Laur- 

 entian. Further, the presence of graphite in association with the 

 apatite in both cases may not be an accidental circumstance, but 

 may depend in both on the association of carbonaceous organ- 

 isms, whether vegetable or animal. 



Again, the liuguliferous sandstone of the Acadian group is a 

 material which, by metamorphism, might readily afford a pyrox- 

 enite with layers of apatite like those which occur in the Lauren- 

 tian. 



The probability of the animal origin of the Laurentian apatite 

 is perhaps further strengthened by the prevalence of animals with 

 phosphatic crusts and skeletons in the Primordial age, giving a 

 presumption that in the still earlier Laurentian a similar prefer- 

 ence for phosphatic matter may have existed, and, perhaps, may 

 have extended to still lower forms of life, just as the appropriation 

 in more modern times of phosphate of lime by the higher animals 

 for their bones seems to have been accompanied by a dimutiou of 

 its use in animals of lower grade. 



