GENERAL RELATIONS OF PLANTS TO TIME. 



433 



— is the Chondrites verisimilis of the Upper Silurian of 

 Scotland. 



The small and peculiar Cryptogamic group of the Charas 

 {Characece) is known to occur in deposits as old as the Jur- 

 assic, by means of their minute spiral seed-vessels or " spor- 

 angia," well known under the general name of " gyrogonites." 



The great group of the Fungi is represented by plants 

 with difficulty susceptible of fossilisation ; but we are, never- 

 theless, able to point to the existence of this section of the 

 Cryptogams in rocks as old as the Carboniferous, owing to 

 the preservation of their mycelium within the woody stem 

 of plants of a higher grade, or from the silicification of the 

 entire fungus. Of the former nature are the mycelial 

 tubules which were detected by Mr Worthington Smith 

 within the axis of a Lepidodendron, and which he has named 

 Peronosporites antiquarius, in allusion to their remarkable 

 likeness to the Fungus which produces the potato-disease 

 (the Feronospora infestans). Of the latter nature are the 

 curious fossils of the Coal-measures of Northumberland, to 

 wliich Messrs Hancock and Atthey have given the name 

 oi Archagaricon (fig. 695). These are oval, rounded, len- 

 ticular, or irregular bodies, under an inch in length, and 

 composed microscopically of irregular, ramifying, tubular 



Fig. 695. — A, A lenticular specimen oi Archagaricon, of the natural size; b. Slice of the 

 same showing the tubes and vesicles, enlarged. Coal-measures. (After Hancock and 

 Atthey.) 



filaments, which terminated in rounded vesicles. Goeppert 

 has described a Carboniferous Fungus {Exstvpulites Neesi), 

 which grows parasitically upon the frond of a fern, and 

 VOL. II. 2 E 



