VIl] ASCOMYCETES. 209 



imperfect to allow of accurate identification. The occurrence 

 of recent fungi as discolourations on leaves is exceedingly 

 common, and the characteristic perithecia or compact and more 

 or less spherical cases enclosing a group of sporangia in certain 

 Ascomycetous species, might be readily preserved in a fossil 

 condition. 



Some examples of possible Ascomycetous fungi have been 

 recently recorded by Potoni^ from leaves and other portions of 

 plants of Peraiian age. There is a distinct superficial resem- 

 blance between the specimens he figures and the fructifications 

 of recent Ascomycetes, but in the absence of internal structure, 

 it would be rash to do more than suggest the probable nature 

 of the markings he describes. For one of the fungus-like 

 impressions Potonid proposes the generic name Rosellinites ; he 

 compares certain irregularly shaped projections on a piece of 

 Permian wood with the perithecia of RoseUinia, a member of 

 the Sphaeriaceae, and describes them as Rosellinites Beyshlagii 

 Pot.' Various other records of similar Ascomycetes-like fossils 

 may be found in palaeobotanical literature '', but it is un- 

 necessary to examine these in detail. Unless we are able to 

 determine the nature of the supposed fungus by microscopical 

 methods our identifications cannot in most cases be of any great 

 value. 



An example of the perithecia of a fungus {RoseUinia 

 congregata [Beck])' has been recorded from the Oligocene of 

 Saxony, which would appear to rest on a more satisfactory basis 

 than is often the case. In this particular instance the small 

 projections on a piece of fossil coniferous stem present a 

 form which naturally suggests a fungus perithecium. In cases 

 where the black spots on a fossil stem or leaf possess a definite 

 form and structure, it is perfectly legitimate to refer them to a 

 group of fungi ; but in very many instances the forms referred 

 to such genera as Sphaerites and others are of little or no value. 



1 Potoni^ (93) p. 27, PI. i. fig. 8. 



2 Eeferenees are given by Potoni§ to illustrations by Zeiller (92^) PI. xv. fig. 6, 

 Grand' Eury (77) PI. xxxiii. fig. 7, and others in whiob possible fungi are 

 represented. 



3 Bngelhardt (87). 



14 



