200 miss m. c. stopes on [May 1909, 



In the delicacy of the preservation of the enclosed tissues also, 

 particularly in the good petrifaction of leaves, twigs, spores, and 

 such small fragmentary structures, the type of petrifaction ap- 

 proximates more closely to that of the roof-nodules. PL IX, 

 fig. 4 shows a transverse section of a stem, and in fig. 3 at b can 

 he seen a fragment of a leaf and other tissue which suffice to show 

 the quality of the preservation which the Japanese nodules may 

 yield. Though portions equally well, or better, preserved could be 

 brought for comparison from the ' roof-nodules ' of the Carboni- 

 ferous, yet the impression derived, after going carefully through 

 hundreds of slides, is that the Japanese nodules show better- 

 preserved small fragments than do the 'roof-nodules.' Moreover, 

 the former give the impression that they had not been subjected 

 to the vicissitudes which had so often damaged the plants in the 

 ' roof-nodules ' before they had been petrified — in fact, judging from 

 the character of the plant-remains alone, the Japanese nodules 

 approximate more nearly to the ' coal-balls ' than to the ' roof- 

 nodules ' in their petrifaction. 



IV. Chemical Analysis op the Nodules. 



The importance of detailed chemical analyses as a foundation for 

 the critical consideration of plant-containing nodules was brought 

 out in the work on the Carboniferous structures, so that, for com- 

 parison with them, the analyses of the nodules here described are 

 essential. Owing to the kindness of Prof. Sakurai, of the Imperial 

 University, Tokio, Mr. Kurihara was persuaded to carry out two 

 analyses of Yubari nodules, while Mr. J. Barnes, of Salford, who 

 carried out those for the previous work, analysed two further 

 samples. 



Analyses by Mr. Kurihara. Japanese Nodules. 



I. II, 



Calcium carbonate, CaCO, 64"29 1 r - o, 4607 "1 n . , « 



Magnesium carbonate, MgC0 3 l-05/ O0Oi 8-06/ O * ltJ 



Iron carbonate, FeCO., 10-50 8"88 



Silica, SiO„ 23-04 30-46 



Water, H,0 037 



Carbon, C 2'07 



Other substances 0'75 4 - 46 



Totals 100-00 100-00 



In these two cases, when the calcium and magnesium carbonates 

 are added together and treated as one, 1 there is seen to be no 



1 This is entirely justifiable, for in a series of nodules from the Carboniferous 

 it was found that calcium and magnesium are interchangeable — the relative 

 proportion of the two elements being widely different, though the total of the 

 two carbonates was roughly constant. 



