In a recent paper the writer described structures which he had found in the Frodingham Ironstone of Lincolnshire. The claim that these structures are fossil fungi is one of more than usual interest, for fossil fungi have not hitherto been recorded from the Jurassic rocks, and, further, the decomposition established by this fungus must have been carried out under marine conditions. Since the publication of this paper criticisms as to the conclusions contained in it have not been wanting, and it is proposed in the present paper to deal with these criticisms and further to furnish a few additional data to supplement those that have already been given.