PERIOD III. 1729-1780 9 



clature, but a second edition, issued twelve years later, is based on the new 

 system: it includes 54 lichen species. 



About this time Adanson' proposed a new classification of plants, 

 dividing them into families, and these again into sections and genera. He 

 transferred the lichens to the Family "Fungi," and one of his sections 

 contains a number of lichen genera, the names of these being culled from 

 previous workers, Dillenius, Hill, etc. A few new ones are added by himself, 

 and one of them, Graphis, still ranks as a good genus. 



In England, Hudson^ who was an apothecary and became sub-librarian 

 of the British Museum, followed Linnaeus both in the first and later editions 

 of the Flora Anglica. He records 102 lichen species. Withering^ was also 

 engaged, about this time, in compiling his Arrangetnent of Plants. He 

 translated Linnaeus's term "Algae" into the English word "Thongs," the 

 lichens being designated as "Cupthongs." In later editions, he simply 

 classifies lichens as such. Lightfoot^, whose descriptive and economic notes 

 are full of interest, records 103 lichens in the Flora Scotica, and Dickson* 

 shortly after published a number of species from Scotland, some of them 

 hitherto undescribed. Dickson was a nurseryman who settled in London, 

 and his avocations kept him in touch with plant-lovers and with travellers 

 in many lands. 



E. Period IV. 1780-1803 



The inevitable next advance was made by Weber" who at the time was 

 a Professor at Kiel. In a first work dealing with lichens he had followed 

 Linnaeus; then he published a new method of classification in which the 

 lichens are considered as an independent Order of Cryptogamia, and that 

 Order, called "Aspidoferae," he subdivided into genera. His ideas had been 

 partly anticipated by Hill and by Adanson, but the work of Weber indicates 

 a more correct view of the nature of lichens. He established eight fairly 

 well-marked genera, viz. Verrucaria, Tubercularia, Sphaerocephalum and 

 Place dium,vfh\c\\ were based on fruit-characters, the thallus being crustaceous 

 and rather insignificant, and a second group Lichen, Collema, Cladonia and 

 JJsnea, in which the thallus ranked first in importance. Though Weber's 

 scheme was published in 1780, it did not at first secure much attention. 

 The great authority of Linnaeus dominated so strongly the botany of the 

 period that for a long time no change was welcomed or even tolerated. 



In our own country Relhan at Cambridge and Sibthorp' at Oxford 

 were making extensive studies of plants. The latter was content to follow 

 Linnaeus in his treatment of lichens. Relhan^ also grouped his lichens 

 under one genus though, in a second edition of his Flora, he broke away 

 from the Linnaean tradition and adopted the classification of Acharius. 



' Adanson 1763. ^ Hudson 1762 and 1778. * Withering 1776. ■* Lightfoot 1777. 



° Dickson 1785. "Weber 1780. ' Sibthorp 1794. ' Relhan 1785 and 1820. 



