372 Profs. King and Rowney on 



pyroxene. As only " chamber-casts " in a mineral silicate 

 were essential in our argument, we necessarily overlooked those 

 alleged to consist of "dolomite or limestone " — though we could 

 have shown that the existence of " chamber-casts " in either 

 of these substances is one of the resultants of pseudomorphism, 

 as was noticed in our description of some spheroids with a 

 siliceous coat, whose interior had been replaced by calcite*. 



13th. We assert that " the configurations presumed to re- 

 present the ' canal-system ' are totally xcitliout any regularity 

 in their form, relative size, or arrangement." Dr. Dawson 

 replies : — " The configuration of the canal-system is quite 

 detinite, though varying in coarseness and fineness." This 

 answer makes it appear as if we referred to its want of definite- 

 ness, which is not the case ; for our point is based on the fact 

 (plainly set forth in figures 28, p. 107, 49^, p. 176, and other 

 two in plate vi. of the 'Dawn of Life') that the " canal-system," 

 though definite, is " totally without any regularity of form." 

 The second part of the answer is remarkable for containing 

 a gratuitous denial to a statement supported by cases that we 

 particularized. 



It was these cases, occurring at Baden, Amity, and other 

 places, that led us on a former occasion to remark : — " Even 

 the zoologist must believe to be a nummuline foraminifer what 

 is structurally an impossihilitas Naturce in having a ' canal- 

 system ' and ' skeleton ' that often ' ran wild,' without either 

 ' chambers ' or a 'cell- wall.' " Other cases have since come 

 to our knowledge testifying to the surprising vagaries of the 

 " creature of the dawn." One is the presence of typical 

 eozoonal structures, beautifully developed, in bands and slabs 

 of ophite occurring in gneiss, transverse to the bedding, at 

 South Mirzaptir, India f. 



We have also to mention that Mr, Burbank, of Lowell, 

 Massachusetts, has found specimens of "Eozoon " in dolo- 

 mitic accumulations of very small extent (the largest ap- 

 pears to be not more than 250 feet in length by 40 or 50 feet 

 wide) enclosed in gneiss, which is for the most part highly 

 crystalHne, and in some places hardly to be distinguished 

 from a true granite. The dolomites are not true stratified 

 deposits, laid down with the gneiss, but have a vein-like 

 character ; and they occui" filling cavities along the line of 



* Proc. Eoyal Irish Acad. vol. i. ser. 2, p. 138. 



t Mr. F. R. Mallet, of the Indian Geological Survey, has kindly fur- 

 nished us with specimens, in which we find both "nummuline layer " and 

 " canal-system," and which we hope some day to have an opportunity of 

 describing. Mr. Mallet has published a mineralogical description of this 

 case in the ' Records of the Geological Surrey of India,' No. 1, 1'872. 



