140 Mr. H. J. Carter on the 



against the so-called " foraminiferous structure of Eozoon 

 canadense" Had the illustration been taken from an in- 

 filtrated specimen, it might have shown the differences to 

 which I have alluded, and so have defeated the author's 

 purpose, while in its present state it is as unintelligible as it is 

 harmless. 



On the other hand, in a vertical section of an infiltrated 

 Nummulite or Orbitoides, in which every part of the structure 

 which was hollow in the recent state is filled with red or 

 brown oxide of iron, while the white substance of the test 

 remaining unaltered contrasts strikingly with the infiltrated 

 tubes (some of which are less than the 6000th of an inch in 

 diameter), the zminfiltrated striae may be observed to run more 

 or less continuously from the circumference to the centre, while 

 the infiltrated lines running in the same direction are not only 

 confined to, but interrupted in their course at intervals by, the 

 chambers of the column to which they belong — being, in fact, 

 the tubuli which run perpendicularly between each pair of cells, 

 viz. that above and that below them, and which, as a matter 

 of course, must be absent in the columns composed of shell- 

 substance only. 



Returning, however, to the " conical element," we observe 

 that each chamber of the lamina (which, it should be re- 

 membered, is not concentric, but spiral) is formed exogenously } 

 and that, although the expansion of the circumference, owing 

 to the increase of size in the test, requires that here and there 

 new columns should be added to fill up the spreading mass, 

 like the shorter medullary rays in a woody stem, still the 

 " tubuli " all progress from within outwards. Each set of 

 tubuli passes from the chamber below to the chamber above it, 

 and no new tubuli are formed after this (that is, backwards) ; 

 so that none belonging to the same column of chambers can 

 pass by a chamber of that column up or down. 



Still, again, it is possible, under certain circumstances, that 

 the chambers of one column may not be on a level with those 

 of the neighbouring column, and therefore that the lenticular 

 chambers and the cylinders of our elementary column may be 

 so placed that in two neighbouring columns, the tubuli of one 

 being opposite the chambers of the other, the tubuli may be 

 said to pass by a chamber, as Dr. Carpenter would have it. 

 But the tubuli of one column of chambers thus passing by the 

 chambers of the neighbouring column is totally different from 

 their passing by these chambers up or down (as I have before 

 stated) in their own column. Were the latter the case, then the 

 relative position of the perpendicular striae around the grain 

 of serpentine, assumed to be cast of a chamber in the so-called 



