_b._ ASCOLICHENS. Lichens are again polyphyletic within this sub-class. The main groups from which they are derived are evident. Whether there has been a series of origins within the different groups or a development from one starting point in each it would be difficult to determine. In any case great changes have taken place after symbiosis became established. The main divisions within the Ascolichens are related to fungi thus: Series 1. Pyrenocarpineae } to Pyrenomycetes. 2. Coniocarpineae } 3. Graphidineae to Hysteriaceae. 4. Cyclocarpineae to Discomycetes. II. THE REPRODUCTIVE ORGANS A. THEORIES OF DESCENT IN ASCOLICHENS It has been suggested that ascomycetous fungi, from which Ascolichens are directly derived, are allied to the Florideae, owing to the appearance of a trichogyne in the carpogonium of both groups. That organ in the red seaweeds is a long delicate cell in direct communication with the egg-cell of the carpogonium. It is a structure adapted to totally submerged conditions, and fitted to attach the floating spermatia. In fungi there is also a structure considered as a trichogyne[981], which, in the Laboulbeniales, is a free, simple or branching organ. There is no other instance of any similar emergent cell or cells connected with the ascogonium of the Ascomycetes, though the term has been applied in these fungi to certain short hyphal branches from the ascogonium which remain embedded in the tissue. In the Ascomycetes examined all traces of emergent receptive organs, if they ever existed, have now disappeared; in some few there are possible internal survivals which never reach the surface. In Ascolichens, on the contrary, the “trichogyne,” a septate hyphal branch extending upwards from the ascogonium, and generally reaching the open, has been demonstrated in all the different groups except, as yet, in the Coniocarpineae which have not been investigated. Its presence is a strong point in the argument of those who believe in the Floridean ancestry of the Ascomycetes. It should be clearly borne in mind that Ascolichens are evolved from the Ascomycetes: these latter stand between them and any more remote ancestry. In the Ascomycetes, there is a recognized progression of development in the form of the sporophore from the closed perithecium of the Pyrenomycetes and possibly through the Hysteriaceae, which are partially closed, to the open ascocarp of the Discomycetes. If the fungal and lichenoid “trichogyne” is homologous with the carpogonial organ in the Florideae, then it must have been retained in all the groups of Ascomycetes as an emergent structure, and as such passed on from them to their lichen derivatives. Has that organ then disappeared from fungi since symbiosis began? There is no trace of it now, except as already stated in Laboulbeniales with which lichens are unconnected.