The list of fossil fungi given by Meschinelli in Saccardo’s _Sylloge Fungorum_[411] includes certain species which are of no botanical value, and should have no place in any list which claims to be authentic. Among the numerous examples of fossil ‘fungi’ which have no claim to be classed with plants, there are some which are in all probability the galleries of wood-eating animals. The radiating grooves frequently found on the inner face of the bark of a pine tree made by species of the beetle _Bostrychus_ might be mistaken for the impressions of the firm strands of mycelial tissue of some Basidiomycetous fungus. In some notes on fossil fungi by J. F. James[412] contributed to the American Journal of Mycology in 1893, it is pointed out that a supposed fungus described by Lesquereux from the Lower Coal-Measures as _Rhizomorpha Sigillariae_[413], bears a strong likeness to some insect-burrows, such as those of _Bostrychus_. “A new fungus from the Coal-Measures” described by Herzer in 1893[414] may probably be referred to animal agency. In any case there is no evidence as to the fungoid nature of the object represented in the figure accompanying Herzer’s description. [Sidenote: BASIDIOMYCETES.] More trustworthy evidence of fossil fungi is afforded by the marks of disease in petrified tissue and by the presence of true mycelia. In examining closely the calcareous and siliceous plant-tissues from the Coal-Measures and other geological horizons, one occasionally sees fine thread-like hyphae ramifying through the cells or tracheal cavities; in many cases the hyphae bear no reproductive organs and cannot as a rule be referred to a particular type of fungus. If the hyphal filaments are unseptate, they most likely belong to some Phycomycetous species; or if they are obviously septate the Mesomycetes or the Mycomycetes are the more probable groups. Occasionally there may be found indications of the characteristic _clamp-connections_ in the septate filaments; a small semicircular branch, which is given off from a mycelium immediately above a transverse wall, bends round to fuse with the filament just below the septum, thus serving as a small loop-line connecting the cell-cavity above and below a cross wall. Such clamp-connections are usually confined to the hyphae of Basidiomycetes and thus serve as a useful aid in identification. A good example of a clamp-connection in a fossil mycelium is figured by Conwentz[415] in his monograph on the Baltic amber-trees of Oligocene age. The stout and thick type of hypha found in some fossil woods agrees closely with that of _Polyporus_, _Agaricus melleus_ and other well-known recent Basidiomycetes.