Floristik, Geographie, Systematik etc. 357 



et une variete, et entin 4 Algues. Les especes nouvelles sont: 

 Catillavia pcruiviutn B. de Lesd., qui croit sur les feuilles mortes 

 de Psamma arenaria, Lecidea piisilla B. de Lesd. et Pleospora Les- 

 dainii Vouaux, trouves sur des morceaux de carton, Phoina fiisis 

 pora Vouaux, parasite de plusieurs Lichens. J. Offner. 



Chevalier, A., Sur l'origine botanique des bois commer- 

 ciaux du Gabon. (C. R. Acad. Sc. Paris. 156. p. 1389—1391. 

 5 Mai 1913.) 



Sauf en ce qui concerne TOkourne {Attcoiimea Klahieana 

 Pierre), dont Tauteur precise la distribution geographiquc, l'origine 

 botanique des bois exportes du Gabon etait jusqu'ici mal connue. 

 Le bois corail ou bois rouge du Gabon est le Pterocarpus 

 Soyaitxii Taub. L'ebene du Gabon est fourni par le Diospyros 

 Evila Pierre, dont les fleurs n'ont pu encore etre etudiees et qui 

 est peut-etre le D. flavescens Gurke du Cameroun. L'acajou du 

 Gabon, qui donne lieu ä un commerce tres important, provient 

 de plusieurs grands arbres de la famille des Meliacees, notamment 

 le Khaya Klainei Pierre, tres voisin du K. ivorensis Chev., s'il ne 

 lui est identique, et d'autres especes de ce genre qui n'ont pu encore 

 etre determinees avec certitnde. . J. Offner. 



Crampton, C. B., Ecolog}^: the best method ofstudying 

 the Distribution of Species in Great Britain. (Proc. Roy. 

 Physical Soc. Edinburgh. XIX. 2. p. 22—36. 1913.) 



The argument, briefly stated, is that the presence of species of 

 plants or animals is insufificiently recorded by using a county or 

 an}" other parochial area, and that such should be based on the 

 plant communities with which they are related. If the plant com- 

 munities were simple and easily defined it would be relatively easy 

 to adapt them but the author recognises the difificulties. The section 

 on the replacement of the natural by the artificial, outlines the 

 extensive changes introduced by deforesting, cultivations and other 

 artificial disturbances of the natural balance. Such changes favour 

 the predominance of certain insects or other foUowers, sometimes 

 as pests, which in primitive conditions may have had a limited 

 distribution. Other causes of disturbance are those induced by bur- 

 ning Calhina moors and heaths, and by the Operations of grazing 

 sheep and cattle. TJie difficulties of the problem of distribution are 

 thus increased so that the records for plants and animals are made 

 on an artificial System. A simple Classification of habitats for obser- 

 vers is suggested: 1) artificial plantations, gardens, fields, and all 

 recently disturbed ground; 2) altered habitats where draining, bur- 

 ning, stocking with animals, interference with woodlands, the in- 

 fluence of towns, or any other factors has changed without previous 

 destruction of the original Vegetation; 3) natural habitats either a) 

 Stahle, or b) migratory as recently defined by Crampton (Bot. Cent. 

 122 p. 290). The original distribution of the more extensive stable 

 and migratory plant-formations in relation to animal distribution is 

 outlined, and the influence of man and his Operations in bringing 

 them into their present condition. In applying ecology as a basis 

 for recording distribution. the faunal and floral relations of stable 

 natural formations such as moorland, heath. and chalk grassland 



