46 British Fungi. 



tlie tissues of a fossil Lepidodendron from the coal 

 measures. Itis culled Peronosporites ant iquarius. W. 

 Sm. Mycelium is met with in the tissues of the vascular 

 cryptogams in early PaLxozoic times. The Ascomycetes 

 are first met with under forms closely resembling Sphse- 

 ria in the Cretaceous rocks, while the Basidiomycetes 

 first appear under the form of Polyporus and allied 

 woody genera in tertiary times. The sequence indicated 

 above, from the P/i?/com?/cefes or algal-like fungi to the 

 Basidiomycetes, agrees with the idea already expressed 

 regarding the evolution of the fungi. The lichens as 

 a group were probably differentiated at a much later 

 geological period than the fungi, and are first met with 

 in a fossil state in tertiary rocks, where such genera 

 as Parmelia, Ramalina, Lecidea, Cladonia, and 

 GrapMs occur, and have continued to the present 

 time. 



LiCnEN-rORMING FuxGi. 



Up to the year 1860 the time-honoured group of 

 Thallogens or Cellular' plants was, considered to con- 

 sist of three well-defined sections, Algse, Fungi, and 

 LicheneSy collectively characterized by the absence of 

 fibro-vascular elements. At the present day it has 

 been shown that onlv two divisions exist, and further 

 that the sujoposed absence of highly differentiated 

 tissues is not supported, but disproved, by recent 

 researches. The following remarks by Dr. Scott ^ 

 explain sufficiently the latter statement : — " Very 



On some recent progress in our knowledge of the Anatomy of 

 Plants, Ann. Bot., vol. iv., p. 147. 



