Vol. 65.] PLANT-CONTAINING NODULES FROM JAPAN. 195 



II. Plant-containing Howies from Japan, considered structurally 



in their Relation to the ' Coal-Balls ' and ' Poof-Nodules ' 

 of the European Carboniferous. By ITaeie C. Stopes, D.Sc, 

 Ph.D., F.L.S. (Communicated by Prof. E. J. Garwood, M.A., 

 Sec.G.S. Bead February 24th, 1909.) 



[Plate IX.] 



Contents. 



Page 



I. Introduction 195 



II. Field-Observations 196 



III. Microscopic Structure of the Nodules 198 



IV. Chemical Analysis of the Nodules 200 



V. Comparison and Contrast with Carboniferous Nodules 203 



VI. Conclusion 203 



VII. Summary 205 



I. Introduction. 



The nodules of which the geological nature is described in this 

 paper are of interest and importance, chiefly because of the plant 

 and animal fossils which they include. The plant-petrifactions are 

 •of a type unknown from the Mesozoic ; these I am describing in a 

 botanical paper in conjunction with Prof. Eujii, of which we hope 

 the first part will be ready for publication in a few months. 



A critical study of the structure and mode of formation of the 

 plant-containing nodules, though a special branch of geological work, 

 is of some value to the students of plants, and in the case of the 

 Carboniferous nodules seemed to repay fully the labour which it 

 entailed. Hence the present short comparative study of the 

 Cretaceous nodules was undertaken. 



Becent work ' on the structure of the Carboniferous nodules 

 brought out decisively what had been spoken of in a general way, 

 namely, the importance of the association of marine organisms with 

 the coals and associated rocks in which they were formed. It also 

 showed that it is when saturated with sea-water that plants seem 

 to stand the best chance of petrifaction, and that only under 

 marine conditions do ' coal-balls ' occur in the coals. As it is in 



1 M. C. Stopes & D. M. S. Watson, 'On the Present Distribution & 

 Origin of the Calcareous Concretions in Coal-Seams, known as " Coal-Balls " ' 

 Phil. Trans. Eoy. Soc. ser. B, vol. cc (1908) pp. 167-218, pis. xvii-xix. 



2 



