The conception of Graphidineae as a whole is puzzling, but one or other characteristic has brought the various members within the series. It is in this respect an epitome of the lichen class of which the different groups, with all their various origins and affinities, yet form a distinct and well-defined section of the vegetable kingdom. _d._ CYCLOCARPINEAE. This is by far the largest series of lichens. The genera are associated with algae belonging both to the Myxophyceae and the Chlorophyceae, and from the many different combinations are produced great variations in the form of the vegetative body. The fruit is an emergent, round or roundish disc or open apothecium in all the members of the series except Pertusariaceae, where it is partially immersed in thalline “warts.” In its most primitive form, described as “biatorine” or “lecideine,” it may be soft and waxy (_Biatora_) or hard and carbonaceous (_Lecidea_), in the latter the paraphyses being mostly coloured at the tips; these are either simple or but sparingly branched, so that the epithecium is a comparatively slight structure. The outer sterile tissue forms a protective wall or “proper margin” which may be entirely pushed aside, but generally persists as a distinct rim round the disc. A great advance within the series arose when the gonidial elements of the thallus took part in fruit-formation. In that case not only is the hymenium generally subtended by a layer of algae, but thalline tissue containing algae grows up around the fruit, and forms a second wall or thalline margin. This type of apothecium, termed “lecanorine,” is thus intimately associated with the assimilating tissue and food supply, and it gains in capacity of ascus renewal and of long duration. This development from non-marginate to marginate ascomata is necessarily an accompaniment of symbiosis. There is no doubt that the Cyclocarpineae derive from some simple form or forms of Discomycete in the Patellariaceae. The relationship between that family and the lower _Lecideae_ is very close. Rehm[993] finds the direct ancestors of _Lecidea_ itself in the fungus genus, _Patinella_, in which the apothecia are truly lecideine in character—open, flat and slightly margined, the hypothecium nearly always dark-coloured and the paraphyses branched, septate, clavate and coloured at the tips, forming a dark epithecium. More definitely still he describes _Patinella atroviridis_, a new species he discovered, as in all respects a _Lecidea_, but without gonidia.