Examination of " Eozoon." 287 



Carpenter has totally ignored the report we gave of our ex- 

 amination of the section in question, we shall give the sub- 

 stance of it, which, with a few additional remarks, will be 

 sufficient to enable the reader to understand the estimate we 

 have formed of the last case he has brought forward. 



We stated that the section was crowded with " canals," 

 distinguished as usual by their semiopacity : intermixed with 

 them were others (encircled by the donor with ink) quite colour- 

 less or transparent, and not visible under full light. They 

 were imbedded in transparent calcite, affected with both rhom- 

 bohedral and macro-diagonal cleavage ; but while in most 

 there was nothing of the kind seen, a few had the appear- 

 ance of possessing calcitic divisional structure. To make our- 

 selves certain with respect to the composition of the trans- 

 parent " canals," we tested them. Obviously, if they con- 

 sisted of calcite, the section, when superficially dissolved (to 

 prevent their dropping out), would display them quite as 

 much acted on by the acid as the matrix. But instead of this 

 being the result, all the transparent " canals " distinguished 

 by a circle in ink were seen projecting out of the remaining 

 portion of the matrix as clear as glass : none showed any traces 

 of cleavage except one, where it was still overlaid by calcite*. 

 This simple test completely demonstrated that the transparent 

 " canals " were entirely siliceous bodies. 



At various times we have been told of the occurrence of 

 "canals filled with carbonate of lime of the same nature" — 

 " of the same crystalline character " — " having the same 

 crystalline axis as that of the matrix." Taking this to refer 

 to cleavage (for such is represented by lines obliquely crossing 

 the transparent " canals " in Dr. Carpenter's fig. 5 ; the same 

 lines, it will observed, are represented (!) equally crossing the 

 semiopaque or u serpentinous canals"), and, considering the 

 absence of ail allusion to chemical and optical evidences con- 

 firmatory of their alleged composition, we are strongly inclined 

 to the belief that the crystalline character observed in the 

 " transparent canals," of late made known, does not belong to 

 them, but to their calcitic matrix ; and, as in other cases of the 

 kind, it is our opinion that there are the strongest grounds for 

 removing this " cardinal fact " from the category of reliable 

 evidence on the side of the " eozoic doctrine." 



* A figure was appended of a portion that had been marked with ink, 

 showing five of the " transparent canals," as seen magnified 210 diameters, 

 and under Webster's condenser with graduating diaphragms. For a full 

 account of this section, and specimens of a similar character, the reader is 

 referred to the ' Proceedings of the Eoyal Irish Academy,' vol. x. pp. 532, 

 534, 535, pi. 44. fig. 11 ; also id. new series, vol. i. p. 132. 



