II. 



THALLOPHYTES, BRYINAE. 



IT lies in the nature of the case that fossil Thallophytes should as 

 a rule be objects of very small importance to the botanist. There are 

 indeed groups among the Thallophytes to which this statement does not 

 apply, those chiefly in which the membranes were calcified while they were 

 still living, and which are therefore found in an unusually perfect state of 

 preservation. Schimper gives us a long list of Fungi and Lichens which 

 have been described by older writers. Where these are not merely spots 

 on leaves, but actual Pyrenomycetes, Discomycetes, and Basidiomycetes 

 growing on leaves or on pieces of fossil wood, they still have no value except 

 as showing what was probable without them, namely, that Fungi formed 

 a part of the ancient floras. Where Polyporei and Lenzites occur, as in 

 the brown coals, it is not surprising that we should also find silicified woods 

 which have been half destroyed by their mycelia. Such mycelia from wood 

 of the Tertiary era have been described by Unger 1 under the generic name 

 Nyctomyces. That there were Fungi in the older formations also is 

 proved by the fragments of thallus with local bladder-like swellings, which 

 are occasionally found in the tissue of stems of Lepidodendron, and which 

 have been figured by Williamson 2 under the name of Peronosporites anti- 

 quarius, Worth. Smith. Similar objects have been mentioned by other 

 writers also, for example by Renault and Bertrand 3 , under the name of 

 Grilletia Sphaerospermii from seeds of the period of the Coal-measures 

 found in the siliceous fragments of Grand' Croix. A form described by 

 Ludwig 4 from coal-seams of the Urals as Gasteromyces farinosus may 

 be nothing more than an aggregate of spores and spore-tetrads of some 

 archegoniate plant. That Bacteria destroyed the substance of dead plants 

 during the period of the Coal-measures, as they do at the present day, is 

 rendered extremely probable by the researches of van Tieghem 5 , who has 

 shown that the macerated vegetable fragments in the pebbles of Grand' 

 Croix exhibit the same progressive demolition of the cell-wall which is 



1 Unger (1). Williamson (1), xi, t. 48, ff. 36, 37 ; t. 54, ff. 28-31. 3 Renault (3) 



(Renault and Bertrand). l Ludwig (3). '" van Tieghem (1). 



