FUNGI. 1499 



Various minute forms of Fungi have been recognised as occurring 

 on the leaves of fossil plants, the oldest of these being found on 

 the leaves of Cycads in Triassic deposits. The fossil leaves of 

 Tertiary plants are very commonly attacked by these parasitic plants ; 

 and other minute forms have been detected in amber. In other 

 cases, the mycelial tubes of a Fungus have been preserved within 

 the woody stem of a plant of higher grade, or the entire Fungus 

 may have undergone silicification. Thus, the mycelial tubes of a 

 Fungus (Peronosporites) have been detected in the tissues of the 

 stems of Carboniferous plants. Messrs Hancock and Atthey have 

 also described, under the name of Archagaricon, certain silicified 

 fossils from the Coal-measures of Northumberland, which they re- 

 gard as referable to the Fungi. These remarkable fossils (fig. 1367) 

 present themselves as oval, rounded, lenticular, or irregular bodies, 

 under an inch in length, which appear on microscopic examination 

 to be composed of irregular, ramifying, tubular filaments, terminat 

 ing in rounded vesicles. 



Lichens are almost unknown as fossils, no example of these plants 

 having been detected in any Palaeozoic or Mesozoic deposit. A 

 few forms have, however, been recognised in amber, and others 

 have been detected on the bark of fossil trees in lignites of Tertiary 

 age. 



