E^SUM^, AND GENERAL DISCUSSION. 535 



"The fabric seems to have consisted of superposed layers of calcareous shell 



substance, whose continuity is frequently interrupted The state of 



preservation of the fossil thus conesponds exactly with that of the Silurian 



Stroniatopora, to which, indeed, it bears a strong general resemblance 



The shelly layers are as distinct in character from the calcite contents of the 

 chambers, as are those of the Numniulites of the pyramid-limestone with 

 which they agree in their remarkable hardness, corresponding with that of 

 porcellanous shell. Altogether I have no hesitation in concurring with Prof. 

 H. A. Nicholson, Prof. Geikie, and Mr. Etheridge in affirming it to be so 

 unmistakably organic, that, if it be claimed by mineralogists as a ' rock struc- 

 ture,' a large number of universally-accepted fossils will have to go along with 

 it. As it is essentially calcareous in its composition, there is no room for the 

 hypothesis of its production by the process of ' mineral segregation,* which is 

 maintained by certain mineralogists .... to have been adei^uate to the pro- 

 duction of the alternating layers of serpentine and calcareous shell-substance 

 in the Canadian Eozoon. And though mineralogical analysis might not im- 

 probably detect small particles of various minerals in its substance, their pres- 

 ence no more establishes its claim to be regarded as a mere rock structure, 

 than does the presence of siliceous films .... in a piece of coral-limestone." * 



Some weeks later Dr. Carpenter acknowledged that the fossil thus 

 elaborately described by him was not calcareous, but that it consisted 

 "of alternating layers of feldspar and quartz — the former simulating 

 an organic structure like that of Stromatopora, and the latter occupying 

 what had been supposed to be the cavities of that structure — together 

 constituting tvhat is known to petrulogists as ' graphic granite.' " f 



In this case, however. Dr. Carpenter might claim that, having made 

 a mistake, he was ready and willing to withdraw his statements after he 

 had been shown to be in error ; and that, having done this, the value of 

 his testimony in regard to the Eozoon was not thereby impaired. As 

 an oftset to this, we will proceed to show that in the case of one of the 

 fundamentally important features of his supposed Foraminifer he was 

 also as much mistaken as he was in regard to the graphic granite, and 

 that he has admitted himself to be so ; but that he did not make this 

 admission until after having persisted in his error for many years, so 

 that we are left entirely in the dark as to how long we must wait before 

 being able to find out what his final opinion will be inamatter of this kind. 

 The point is this : Dr. Carpenter, after having, at various times during 

 an interval of fifteen years, called attention to the so-called " proper 

 wall" or "nummuline layer" of the Eozoon, the existence of which he 

 said that he had been able "most satisfactorily to determine," and which 

 he considered to be '•' a point of the highest importance in the determiha- 



* Nature, 1S76, XIV. -9. t Ibid., 68. 



