Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/211

 ophites, though some are wanting in other ophites, just as they are not always present in the Eozoonal rock of Canada.

Serpentine has been described as having been deposited in the cavities of Eozoon, and having taken the place of its sarcode ; but the authors criticised all the quoted analogies of such a precipitation of any siliceo-magnesian substance, which they disbelieve, and put aside glauconitic infiltration as beside the question.

Considered geologically, with referrence to its occurrence in a metamorphic rock, the authors regarded the Eozoon as an organic impossibility ; and they asked why it should never be found in anything but crystalline or semicrystalline rocks — in ophites or ophicalcites of widely different ages. Particularly they found eozoonal structure in the Liassic ophite of Skye ; and this they described in full. They criticised Sterry Hunt's change of opinion, who used to think that the serpentinous rocks of Canada were once earthy amorphous silicates, and afterwards metamorphosed, but who now supposes they were deposited in a crystalline state ; and they asked why, if so, may not all the Laurentian rocks have been so deposited ? In conclusion, they totally denied that Eozoonal structure has anything to do with any organism, and repeated that, like all analogous conditions of serpentine, chondrodite, &c., it is of purely mineral origin.

Discussion.

Prof. Ramsay had been struck long ago by the organic appearance of the structure now regarded as Eozoon. He had also felt a difficulty in accounting for the existence of large masses of limestone, except by the operation of organisms living in the sea, in which such deposits had been formed. He could not imagine the sea-water so overcharged with calcareous matter as spontaneously to deposit limestone.

Mr. Parker, on examining the various parts of the Eozoon as shown him by Dr. Carpenter, had been able to recognize in them similar structures to what he had already met with in recent Foraminifera.

Prof. T. Rupert Jones accounted for the difficulty that sometimes existed in recognizing Eozoonal structure by the contortion of the containing beds subsequently to their deposition.

Dr. Duncan had been struck in the earlier known specimens of Eozoon by the shape of the tubules of the canals: he had never seen similar outlines in inorganic bodies.

Dr. Carpenter need not repeat the grounds on which he regarded Eozoon as an organic structure. He objected to criticisms unless founded on examination of actual specimens, and regretted that Prof. King had not examined the large collection of specimens in his (Dr. Carpenter's) collection. A specimen which Sir William Logan had brought from Canada contained much iron, and had the Canal-system wonderfully preserved; and it presented this character — that the larger branches were infiltrated with serpentine, and the middle branches with sulphide of iron, while the smallest branches were filled with carbonate of lime, of the same nature as the

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