1871.] 201 [Perry. 



lier studies in this direction, at once to detect the falsity of the 

 inference that had been drawn, and to indicate what all the evidence 

 thus far gathered shows to be the true nature of the masses in ques- 

 tion. I found, and have since substantiated by various and careful 

 cross examinations, what the advocates of the organic structure of 

 the u Eozoon " seem never to have suspected, that the limestones 

 under consideration are not to be regarded as stratified masses at all; 

 that, while they may appear, on casual inspection, to be laminated, 

 they are really foliated, and the appearance of stratification is thus to 

 be accounted for in another way; and that being unstratified they 

 are not either almost altogether, as has been affirmed of many such 

 rocks, or in any degree made up of organic remains. These calca- 

 reous deposits, as should be constantly borne in mind, do not occur 

 in an uninterrupted line, or crop out in ranges at all uniformly con- 

 tinuous, as is usually the case with sedimentary beds. They are 

 isolated masses, generally of greatly varying size (though in the 

 Chelmsford series more uniformity may be observed in this particu- 

 lar) and as ordinarily found upon the surface, they almost invaria- 

 bly appear only at irregular intervals. 



It should be also remarked that the limestones at Chelmsford, like 

 other kindred masses, are of a lenticular shape. They occupy, or 

 rather they once occupied — for the limerock has been mostly re- 

 moved for economical purposes — pockets, irregular and uneven cav- 

 ities, or in most cases, oven-shaped spaces, more or less lenticular, 

 which were clearly produced by the disturbance of the main for- 

 mation. This, at Chelmsford, consists almost entirely of gneiss and 

 of gneissoid rocks. The cavities containing the limestone were once 

 plainly overarched by the accompanying gneiss. In places the gneiss 

 now so overarches some of them, and beyond question it so over- 

 arched them all before denudation took place, as to make it evi- 

 dently impossible that extraneous fossils, or any other solid foreign 

 bodies, could have been carried in and deposited in a continuous series 

 beneath the summits, and all along the sides, of the gneissic arches. 



Again, these lenticular masses of limestone have that banded struc- 

 ture which is peculiar to one class of veins. They are foliated, in 

 the strict sense of the epithet, there being a series of leaves, or of 

 leaf-like layers, and these having a regular sequence from the walls 

 toward the centres of the cavities. And to this succession peculiar 

 evidence is borne ; for there is associated with the successive bands a 

 like succession of different minerals. The orderly occurrence of 



