This fungus bears a close resemblance to Peronosporites antiquarius, but it is impossible to determine its precise botanical position without further data. In Cash and Hick’s paper in which the above fungus is briefly dealt with, some small spore-like bodies are figured which the authors speak of as possibly a Myxomycetous fungus[432]. There is however no sound reason for such a supposition.
As examples of Ascomycetous fungi found in silicified wood of Tertiary age, two species may be quoted from Felix.
Cladosporites bipartitus Felix[433], fig. 43, 3.
The mycelium and conidia of this form were discovered in some Eocene silicified wood from Perekeschkul near Baku, on the shores of the Caspian. The conidia are elliptical or pyriform in shape and divided by a transverse septum into two cells. No traces were found of any special conidiophores. The mycelium consists of septate branched hyphae, rendered conspicuous by a brown colouration. Felix compares the fossil with the recent genera Cephalothecium and Cladosporium.
Haplographites cateniger Felix[434], fig. 43, 4.
The conidia of this form were found to be fairly abundant in the silicified tissue investigated by Felix; they occur usually in chains of 2 to 6 conidia having an ovoid or flask-shaped form, with a thick membrane (fig. 43, 4). The mycelium consists of branched hyphae divided into long cylindrical cells by transverse septa; occasional instances were found of an H-shaped fusion between lateral branches of parallel hyphae.
Felix compares this species with examples of the genera Haptographium and Dematium of the family Sphaeriaceae; it was found in the woody tissue of a dicotyledonous stem from Perekeschkul.
Zygosporites sp.
The object represented in fig. 41 F consists of a stalked spherical sac bearing a number of radiating arms which are divided distally into delicate terminations. We find similar bodies figured by Williamson[435] in his IXth and Xth Memoirs on the Coal-Measure plants; he includes some of them under the generic term Zygosporites, and compares them with the zygospores of the freshwater algae Desmideae. Hitherto these spore-like fossils have only been recorded as isolated spheres, but in the example shown in fig. 41 F there is a distinct tubular and thin-walled stalk attached to the Zygosporites. The specimen was found in the partially disorganised cortical tissue of a Lyginodendron stem from the English Coal-Measures. It is difficult to decide as to the precise nature of the fossil, but the presence of the hyphal stalk points to a fungus rather than an alga as the most probable type of plant with which to connect it. It may possibly be a sporangium of a fungus comparable with the common mould Mucor, or it may be a zygospore formed by the conjugation of two hyphae of which only one has been preserved.
POLYPORUS.