196 hiss m. c. stopes on [May 1909,. 



the coal-balls that such storehouses of tissue-petrifactions are to 

 be found, they are of particular importance to the plant-anatomist. 

 This led me to search for marine coals of ages other than Carbo- 

 niferous, in the course of which a valuable suggestion, followed by 

 specimens, was made by Prof. Pujii, of Tokio. His information 

 appeared to be confirmed by the publication of the Imperial Geo- 

 logical Survey of Japan, wherein it was stated * (p. 104) : 



'But at Yiibari and other coal-mines the distinction between the Tertiary and 

 Cretaceous formations seems not very clear, coal-seams being also found asso- 

 ciated with Ammonites beds.' 



As a result of these clues, in particular the tAvo specimens sent by 

 Prof. Fujii, which much resembled ' roof-nodules/ I set out in 

 search of Mesozoic ' coal-balls ' in Japan, aided by a grant from 

 the Poyal Society. No coal-balls were found, but the nodules here 

 described contain plant-tissues as well preserved as in the true coal- 

 balls. They are thus of almost equal value to the plant-anatomist, 

 and may prove of considerable botanical importance when fully 

 studied, as no such material is known of Mesozoic age from any 

 other horizon. The following account of the geological nature and 

 structure of these nodules may, therefore, be of interest. 



The work on the subject of coal-balls which has been already 

 mentioned (Stopes & "Watson, op. cit.) gives a comparatively com- 

 plete account of their structure and mode of formation. The facts 

 presented in that paper must be assumed to be already in the 

 possession of the reader of this, for it is not possible to recapitulate 

 here all the results of the previous work which form the foun- 

 dation of the standpoint from which the present subject has been 

 considered. 



II. Field -Obseevations. 



The Cretaceous rocks which yielded the plant-containing nodules 

 form thick beds in the Northern Island of Japan, Hokkaido. The 

 age and general distribution of these beds has been practically 

 settled by Dr. Yabe's 2 work on the ammonites contained in them. 

 As the plant-containing nodules which we are considering include 

 one or more species of ammonites in nearly every case, his results as 

 regards age apply equally to the plants, which are therefore un- 

 doubtedly Upper Cretaceous. 



Yabe's paper is concerned only with a detailed description of the 

 ammonites, but in his introductory remarks (p. 5) he gives a short 

 account of the entire Cretaceous series of Hokkaido. I may here 



1 ' Outlines of the Geology of Japan, to accompany the Geological Map of the 

 Empire.' Compiled by the officials of the Imperial Geological Survey of Japan, 

 Tokio (1902) pp. 1-251. 



2 H. Yabe, ' Cretaceous Cephalopoda from the Hokkaido ' parts i & ii, 

 Journ. Coll. Sci. Imp. Univ. Tokio, vols, xviii & xix (1903 & 1904). 



