In the following necessarily brief account of families and genera, the “spermogonia” or “pycnidia” have in most cases been left out of account, as in many instances they vary within the family and occasionally even within the genus. Their taxonomic value is not without importance, but, in the general systematic arrangement, they are only subsidiary characters. An account of them has already been given, and for more detailed statements the student is referred to purely systematic works. There are two main types of spore production in the “pycnidia” which have been shortly described by Steiner[1034] as “exobasidial” and “endobasidial.” In the former the sporophores are simple or branched filaments, at the apices of which a short process grows out and buds off a pycnidiospore; in the latter the spores are budded directly from cells lining the walls or filling the cavity of the pycnidium. The exobasidial type is more simply rendered in the following pages by “acrogenous,” the endobasidial by “pleurogenous” spore production. In many cases the “spermogonia” or “pycnidia” are still imperfectly known. In designating the gonidial algae, the more comprehensive Protococcaceae has been substituted for _Protococcus_, as in many cases the alga is probably not _Protococcus_ as now understood, but some other genus of the family[1035]. SUBCLASS I. ASCOLICHENS SERIES I. PYRENOCARPINEAE It is on mycological grounds that Pyrenocarpineae are placed at the base of lichen classification. There is no evidence that the series was first in time. I. _MORIOLACEAE_ This family was described by Norman[1036] in 1872 from specimens collected by himself in Norway or in the Tyrol, on soil or more frequently on trees. There seems to have been no further record, and Zahlbruckner, while accepting the family, suggests that an examination or revision may be necessary. The thallus is crustaceous. The algal cells, Protococcaceae, occur either in groups (sometimes stalked) surrounded by a plectenchymatous wall and called by Norman “goniocysts,” or they form nests in the thallus termed “nuclei” which are surrounded by a double wall of plectenchyma, colourless in the interior and brown outside. Norman invented the term “Allelositismus,” which may be rendered “mutualism,” to indicate this peculiar form of thallus. The species of _Spheconisca_ are fairly numerous on poplars, willows and conifers: Algae in “goniocysts” 1. *Moriola Norm.[1037] Algae in double-walled “nuclei” 2. *Spheconisca Norm. II. _EPIGLOEACEAE_ The family consists of but one genus and one species, _Epigloea bactrospora_, and, according to Zahlbruckner, further examination is necessary to make certain as to the lichenoid nature of the plant.