Vol. 65.] PLANT-CONTAINING NODULES FROM JAPAN. 197 



state that Dr. Yabe's kindness in lending to me his field-maps 

 made the present work less arduous than otherwise would have 

 been the case. According to Yabe, the Cretaceous is purely marine, 

 and the beds lie (' after Jimbo and the general usage of Japanese 

 geologists ') immediately above the Palaeozoic, while they gradually 

 merge into the Tertiary above, from which it is difficult to separate 

 them. Yabe divides the Cretaceous into three main divisions : — 

 I, the Lower Ammonite-Beds ; II, the Trir/oma-S&ndstone Series ; 

 and III, the Upper Ammonite-Beds. It is in the last-named that 

 the nodules which we are now considering are found. 



At first I hoped to find coals iuterbedded with marine rocks in 

 which were true ' coal-balls,' and for this purpose a number of 

 ooal-mines in the district were carefully examined. There was, 

 however, no trace of any true nodule or coal-ball in the coals, 

 although large silicified masses occurred in some seams in great 

 numbers, which are apparently identical with those in the Tertiary 

 coals of Kyushu in Southern japan. These consist almost entirely 

 of silicates and carbon, and contain no delicate tissue-petrifactions, 

 as they enclose only the wood of big trunks. As their nature and 

 origin appear to be fundamentally different from those of coal-balls, 

 they will be considered in a separate paper. The examination of 

 the mines left me in grave doubt as to whether any of the coals 

 above the Cretaceous were truly marine, for in those cases in 

 which Cretaceous fossils were reported to have been found in the 

 mines, the most careful examination and the closest questioning of 

 the local authorities and workmen could bring to light no suggestion 

 of their existence within a hundred feet of the coal itself. Hence 

 it was concluded that the plant-nodules could not correspond either 

 to the ' coal-balls ' (from the seam itself) or to the ' roof-nodules ' 

 (from the roof-rocks immediately above the coal), which are the 

 sources of petrified plants in the Coal-Measure Series of England. 

 The Japanese coals are presumably freshwater deposits, and lie 

 some distance above the shales in which the nodules are found. 



Before proceeding, it is necessary to say a few words about the 

 nature of the ground which the geologist must traverse in these 

 regions, as it largely accounts for the relative uncertainty that 

 exists about points which could be fully known in an inhabited 

 part of the country. In the immediate neighbourhood of the 

 coal-mines themselves are clearings, roads, and even railways for 

 the transport of the coal, but a few yards from the mining settle- 

 ment one enters virgin, trackless forest. Here the trees grow 

 thickly, and the ground is entirely covered with a tangle of a genus 

 of bamboo-grass 6 feet high, and a variety of prickly shrubs 

 beneath the trees. To force a path through this is a great labour, 

 and is entirely . profitless, for the geology of the ground is com- 

 pletely hidden by the rank vegetation. Hence, beyond the mines, 

 where there are no footpaths, the only place to find exposures 

 and the only possible track to follow is the bed of a river. The 



