536 



THE AZOIC SYSTEM AND ITS SUBDIVISIONS. 



tton of (he affinities ofEozoon," * has recently admitted that he was entirely 

 mistaken in all this, and has conceded the fact claimed by the opponents 

 of the organic character of this supposed fossil, that this nummuline 

 layer was simply the mineral chrysotile in one of its ordinary forms of 

 occurrence, namely, in hands or layers of finely fibrous material.t 



In describing certain rocks of New Hampshire called by him "green- 

 stones," and assigned to the Huronian formation by Prof. C. H. Hitch- 

 cock, Dr. Hawes made the following statements : 



"In the microscopic study of these massive chloritic rocks, or metadiahase, 



I have found certain forms which appear to be of organic origin It has 



the structure of a tabulated coral, resembling much a Cliatetes; but on account 

 of its minuteness, in connection with other characters, there is little question 

 but that it is a fragment of a rhizopod mass or foraminifcr ; % and a close 



resemblance to a Stromatopora will he noticed These forms seem to be 



abundant in the rock The specimen figured is the most perfect that I 



have seen ; hut smaller fragments are abundant, and as they are apparently 

 alike in dimensions, they sustain the supposition of the organic origin of all. 

 .... These forms, distributed through the massive rock, have a structure, 

 . . . . which cannot he attributed to crystallization. They seem to make it 

 evident that rhizopods must have been living over the sea bottom during the 

 accumulation of these sediments, and became buried in the mud which is now 



the material of the rock. These forms are composed of silicates Yet 



upon placing a drop of acid upon one of them it effervesced for a short time, 

 showing that carbonate of lime existed in it — perhaps part of that of the 



original foraminifcr. 



** The presence of these remains of rhizopods in the mctadiabasc is addi- 

 tional evidence of the sedimentary origin of these rocks ; and they also confirm 

 the view that the metamorphism was feeble in its degree, since it allowed of 

 the preservation of these forms Everything points to quiet waters dur- 

 ing the original deposition,5 and finally to gentle metamorphism." || 



♦ Quart. Jour. Geol. Soc, XXL 62. 



t This retraction, on the part of Dr. Carpenter, of one of the most essential fea- 

 tures of the Eozoon has not, so far as we know, been published; but it was made in 

 public at a meeting of the Boston Natural History Society, and repeated in private 

 at the Museum in Cambridge, in presence of one of the authors of this paper. 



t The reader will be tempted, at this point, to exclaim with Dr. Carpenter, 

 **Tndy, as I have had occasion before to say, 'there is no limit to the posaibiJJtiee 



of Foramiuifera ! * " (Nature, XIV. 9.) 



§ It may be said that these rocks have been examined by Dr. Wadsworth, and 

 their microscopic characters found to be identical with those of the altered diabases 

 of Eastern Massaidmsctts, which occur in nnmistalcable dikes, cutting argillite ( Primor- 

 dial ?). The field evidence, Mr. Huntington states, indicates that Hawes's rocks 



were in dikes. 



II Am. Jour. Sci., 1876 (3), XII. 129-137. 



