THE PRESERVATION OP EOZOON. 121 



remarkable for tlie manner in which their reticulated structure, 

 which is similar to that of modern Crinoids, has been injected 

 with a silicious substance, which is seen distinctly in slices, 

 and still more plainly in decalcified specimens. This filling is 

 precisely similar in appearance to the serpentine filling the 

 canals of Eozoon, the only apparent difierence being in the 

 forms of the cells and tubes of the Crinoids, as compared with 

 those of the Laurentian fossil ; the same silicious substance 

 also occupies the cavities of some of the small shells, and 

 occurs in mere amorphous pieces, apparently filling interstices* 

 From its mode of occurrence, I have not the slightest doubt 

 that it occupied the cavities of the criuoidal fragments while 

 still recent, and before they had been cemented together by 

 the calcareous paste. This silicious filHng is therefore similar 

 on the one hand to that effected by the ancient serpentine of 

 the Laurentian, and on the other to that which results from the 

 depositions of modern glauconite. The analysis of Dr. Hunt, 

 which I give below, fully confirms these analogies. 



I may add that I have examined under the microscope por- 

 tions of the substance prepared by Dr. Hunt for analysis, and 

 find it to retain its form, showing that it is the actual filling 

 of the cavities. I have also examined the small amount of 

 insoluble silica remaining after his treatment with acid and 

 alkaline solvents, and find it to consist of angular and rounded 

 grains of quartzose sand. 



The following are Dr. Hunt's notes : — 



"The fossiliferous limestone from Pole Hill, New Brunswick, 

 probably of Upper Silurian age, is light gray and coarsely 

 granular. "When treated with dilute hydrochloric acid, it 

 leaves a residue of 5"9 per cent., and the solution gives 1"8 per 

 cent, of alumina and oxide of iron, and magnesia equal to 1'35 

 of carbonate — the remainder being carbonate of lime. The 

 insoluble matter separated by dilute acid, after washing by 

 decantation from a small amount of fine flocculent matter, 

 consists, apart from an admixture of quartz grains, entirely of 

 casts and moulded forms of a peculiar silicate, which Dr. 

 Dawson has observed in decalcified specimens filling the pores 

 of crinoidal stems ; and which when separated by an acid. 



