322 



NATURE 



[July 31, 1890 



however, one of a chain of coal-fields which will, in my 

 opinion, ultimately be proved to extend under the newer 

 rocks between Dover and Somerset, along the line of the 

 North Downs, in long narrow east and west troughs. It 

 is probably a continuation beneath the Straits of Dover 

 of the coal-measures struck at Calais (see Fig. 2). 



The further question as to the value of these fields may 

 be answered by the amount of coal in the fields which 



are now being worked in Westphalia, Belgium, France, 

 and Somersetshire. The WestphaHan coal-field contains 

 294 feet of workable coal, distributed in 117 seams; that 

 of Mons, 250 feet, in no seams; and that of Somerset, 

 98 feet, in 55 seams. The North French coal-field in 

 1887 yielded 7,119,633 tons, and gave employment at 

 the pits to 29,000 men, and is rapidly increasing its 

 output. 



jleasure 



Fig. 2 — Probab'e Range of Coal-measure; betweea Dover and Calais. 



It may be inferred that the buried coal-fields which 

 await the explorer in the North Downs are in all prob- 

 ability not inferior to these. Godwin-Austen, in his 

 memorable paper before the Geological Society, in 1855, 

 said that if one of these buried fields were once struck 

 in South-Eastern England, their exploration would be 

 an easy matter. It has been struck at Dover, and the 



necessary base is laid down for further discoveries, which 

 in all probability will restore to South-Eastern England 

 the manufactures which have long since fled away to the 

 coal districts of the west and north, and which will put 

 off by many years the evil day when the energy stored up 

 in the shape of coal in these islands shall have been 

 spent. 



RECENT ADDITIONS TO THE LITERA TURE 

 OF INSULAR FLORAS. 



The Laccadives. 

 'HPHESE small islands, fourteen in number, are situated 

 •^ between 10° and 14° N. lat, and at 120 to 180 miles 

 from the Malabar coast of India. They are of coral 

 formation, almost without exception portions of atoll 

 rings, and nowhere elevated more than twenty feet 

 above the sea, so that storm-waves sometimes 

 sweep completely over them. In 1847 such a wave 

 destroyed 1000 of the small population, and there have 

 been equally disastrous cyclones in much more recent 

 times. Indeed, according to Hunter's Imperial Gazetteer 

 of India, the islands, which have an area of two to three 

 square miles, are nowhere more than ten or fifteen feet 

 above the level of the sea. In 1871 the population was 

 estimated at about 13,500, and the almost sole cultivation 

 is the coco-nut palm. It is supposed that the abundance 

 of this palm may have attracted the first settlers, but as 

 that event occurred more than 350 years ago— how much 

 more it is impossible to say— this point must remain 

 uncertain. The total annual value of the exports, con- 

 sisting almost entirely of the products of the coco-nut 

 palm, is said to be about ^17,000. From the physical 

 character of the group, it was not expected that the flora 

 contained any endemic element, but until quite recently 

 there was no published account of the vegetation, beyond 

 broad generalizations. Dr. D. Prain, Curator of the 

 Calcutta Herbarium, has supplied the want in the 

 " Memoirs by Medical Officers of the Army of India," 

 Part v., where he gives an enumeration and analysis of 

 all the plants hitherto known by him to have been collected 

 in the islands, and he has since communicated to the 

 writer a list of some twenty additional species. Briefly, 

 the vegetation consists, apart from cultivation, of very 

 widely dispersed plants — whose wide area is due to ocean 

 currents, birds, or winds — plus a number of weeds of 



NO. 1083, VOL. 42] 



tropical cultivation. Dr. Prain has not visited any of the 

 islands himself, and collectors have not concerned them- 

 selves with the question of colonization of plants from 

 drift-seeds or from seeds conveyed to the islands by 

 carpophagous birds ; hence his deductions are mainly 

 based on probabilities, which he discusses in considerable 

 detail, followed by a table giving the full distribution of 

 all the plants then known to him from the islands. These 

 number eighty, including seventeen purely cultivated 

 plants. It is interesting to know what is cultivated, of 

 course ; but it is undesirable to encumber the distri- 

 butional tables with plants of this category. Dr. Prain 

 estimates that the presence of eleven species is certainly 

 due to the sea, seventeen probably so, and twenty-two 

 possibly so ; whilst birds are regarded as the agents in 

 two, three, and five instances respectively. The two ferns 

 collected in the island of Anderut are set down with 

 certainty to the wind, and two or three other plants 

 probably to the same agency. The rarity of ferns 

 seems to be accounted for, in part at least, by the ex- 

 treme flatness of the islands rather than by unfavourable 

 conditions, for Dr. Treub found eleven species of ferns on 

 the elevated part of Krakatab only three years after the 

 great eruption, which absolutely destroyed all the vege- 

 tation previously existing, and covered the island with a 

 volcanic deposit of intense heat from one to sixty yards 

 in thickness. 



One common tree in the vegetation of many islands of 

 the Indian Ocean we miss in Dr. Prain's list, and that is 

 Cordia subcordata, the iron-wood of the Keeling Islands. 



The Kuriles. 

 Mr. Kingo Miyabe, lately appointed Professor of 

 Botany at the Agricultural College, Sapporo, Japan, and 

 formerly a student at Harvard, U.S., and for a short time 

 in this country, is the author of a " Flora of the Kurile 

 Islands," which is published in the Memoirs of the 

 Boston [U.S.] Society of Natural History, vol. iv., No. 7. 



