PROCEEDINGS OF GEOLOGICAL SOCIETIES. 



263 



Tlie intimate relationship traceable between the Tertiary and Japanese 

 floras in the numerous characteristic types common to both ; the issue of 

 the ordinal and generic comparisons given above ; the larger proportion 

 of ligneous species in the Japanese than in the Eastern American flora ; 

 and the number of types peculiar, at the present day, to Eastern America 

 and Eastern Asia, compared with the few restricted to Europe and 

 America, the speaker contends, favour the view advanced by Professor 

 Asa Gray in reference to plants and by Mr. Darwin as to animals, viz. 

 That the migration of forms to which is due the community of types 

 in the Eastern States of North America and the Miocene of Europe, took 

 place to the North of the Paciflc ; an overland communication, it may 

 be supposed, having existed during the Tertiary time somewhere about 

 Behring's Straits or the line of the Aleutian Islands. This view is 

 confirmed by the occurrence of Miocene vegetable remains in North-west 

 America (including genera yet growing in Japan but lost to America), 

 which prove, further, the temperature of these latitudes to have been 

 at that time sufficiently high to have permitted their existence so far 

 north. 



The evidence in favour of the 'Atlantis ' might, moreover, be expected 

 to have been more marked in the existing vegetation of the Atlantic 

 Islands than is the case. Professor Heer points out the genera Clethra, 

 ]3ystropogo7i, Cedronella, and Oreodaplme as common to the Atlantic 

 Islands and America. Japanese species-, however, have been described of 

 Clethra and Cedronella ; and Messrs. Webb and Berthelot limit Bystro- 

 pogon to Atlantic Island species. Oreodaplme occurs in South Africa 

 and adjacent islands. 



A connection between these Islands and Europe, at perhaps a late 

 period of the Tertiary, may be considered as highly probable from the 

 predominance of Mediterranean forms in their flora. The few genera 

 characteristic of the Tertiary which they possess may have been derived 

 during this connection ; but the hypothesis tliat a continent should ha\^e 

 extended westward as far as America, the speaker considered the available 

 botanical evidence did not in the least substantiate. 



HoYAL Institution of Geeat Beitain. — May 23. — " On Coal." By 

 Warington W. Smyth, Esq., E.E.S. The speaker selected one portion 

 onl}^ of this large subject ; and, neglecting chemical and statistical and 

 mining particulars with reference to this important mineral, confined him- 

 self to the physical conditions under which it is found to occur. 



Mr. Smyth described the nature of the various substances with which 

 the coal is associated ; and comparison was made between the total thick- 

 ness of carboniferous rocks or coal-measures of different districts, as well 

 as between the total thickness of coal (in the aggregate of the seams) ; 

 hence we have one reason for not estimating the value of a coal-field merely 

 by its area, as laid down in a geological map. Thus, the well-known Dur- 

 ham field, with a thickness of measures of about 2000 feet, has a total 

 thickness of coal of 50 feet ; the Derbyshire, 2000, and almost twice the 

 thickness of coal; the North Staffordshire, 6000 feet of measures, and 130 

 of coal ; whilst the South Welsh and Saarbriicken fields exhibit thicknesses 

 of 12,000 to 15,000 feet, with a proportionate increase, especially in the 

 latter, of coal. A second reason for mistrusting area as a criterion of the 

 importance of a coal-district, is the various forms into which the coal-mea- 

 sures have been thrown or moulded by agencies operating at a later date 

 in the earth's crust, whence some districts may exhibit by outcrops an in- 

 dication of the full amount of their entire contents, whilst in others the 

 beds pass with a gradual inclination beneath newer formations, through 



