WORK ON FOSSIL PLANTS BEGUN 253 



Zamia gigas." His full paper, in which he maintained the 

 Cycadeari affinities of the flower-like fossils, was written soon 

 afterwards, but met with a series of misfortunes, and was not 

 finally published till 1870, in the Transactions of the Linnean 

 Society, before which body it had been read in 1868. William- 

 son was admittedly right in connecting the floral organs with 

 the so-called Zamia foliage, and his interpretation of the com- 

 plicated structure was as good as was possible in the then state 

 of knowledge. The true nature of these fossils, now known 

 by the name Williarnsonia, given them by Mr Carruthers, 

 could only be understood at a much later date in the light of 

 Dr Wieland's famous researches on the American Bennettiteae, 

 and has quite recently been made clear in a memoir by Prof. 

 Nathorst. Perhaps, even now, some points remain doubtful. 



Early in the fifties Williamson made some rough sections of 

 a Calamite which came into his hands, and this was the begin- 

 ning of his most characteristic line of work. A remarkable 

 internal cast of a Calamite, figured by Lyell in his Manual of 

 Geology in 1855, led to a correspondence with M. Grand'Eury, 

 now so famous as the veteran French palaeobotanist. William- 

 son at that time had no intention of entering on the serious 

 study of Carboniferous plants, for Binney was already in the field. 

 Grand'Eury's letter, however, caused him to look up his old 

 sections, which he found differed from the Calamitean stems 

 figured by Binney. Matters for a time moved slowly, and 

 Williamson's specimen was only described in 1868 in the 

 Manchester Memoirs. This fossil, which he named Calamopitus, 

 is now known as Arthrodendron, and is a distinct type of Cala- 

 marian stem, intermediate between the common Calamites or 

 Arthropitys, and the more elaborate Calamodendron of the Upper 

 Coal Measures. 



Williamson was now fairly started on his Carboniferous work. 

 His first memoir on the Organisation of the Fossil Plants of the 

 Coal Measures was communicated to the Royal Society on 

 November n, 1870. It is amusing to find that the secretaries 

 objected to the memoir being called Part I, since it bound the 

 society to publish a Part II! Nineteen Parts were published, 

 the last in 1893. 



