In only one extremely rare lichen, _Pyrenothamnia Spraguei_ (N. America), is there fruticose development: the thallus, round and stalk-like at the base, branches above into broader more leaf-like expansions. _b._ THALLUS OF CONIOCARPINEAE. At the base of this series are genera and species that are extremely elementary as regards thalline formation, with others that are saprophytic and parasitic. The simplest type of thallus occurs in Caliciaceae, a spreading mycelium with associated algae (Protococcaceae) collected in small scattered granules, resembling somewhat a collection of loose soredia. The species grow mostly on old wood, trunks of trees, etc. In _Calicium_ (_Chaenotheca_) _chrysocephalum_ as described by Neubner[1004] the first thallus formation begins with these scattered minute granules; gradually they increase in size and number till a thick granular coating of the substratum arises, but no cortex is formed and there is no differentiation of tissue. The genus _Cyphelium_ (Cypheliaceae) is considered by Reinke to be more highly developed, inasmuch as the thalline granules, though non-corticate, are more extended horizontally, and, in vertical section, show a distinct differentiation into gonidial zone and medulla. The sessile fruit also takes origin from the thallus, and is surrounded by a thalline amphithecium, or rather it remains embedded in the thalline granule. A closely allied tropical genus _Pyrgillus_ has reached a somewhat similar stage of development, but with a more coherent homogeneous thallus, while in _Tylophoron_, also tropical or subtropical, the fruit is raised above the crustaceous thallus but is thickly surrounded by a thalline margin. The alga of that genus is _Trentepohlia_, a rare constituent of Coniocarpineae. A much more advanced formation appears in the remaining family Sphaerophoraceae. In _Calycidium_, a monotypic New Zealand genus, the thallus consists of minute squamules, dorsiventral in structure but with a tendency to vertical growth, the upper surface is corticate and the mazaedial apothecia—always open—are situated on the margins. _Tholurna dissimilis_, (Scandinavian) still more highly developed, has two kinds of rather small fronds corticate on both surfaces, the one horizontal in growth, crenulate in outline, and sterile, the other vertical, about 2 mm. in height, hollow and terminating in a papilla in which is seated the apothecium. Two other monotypic subtropical genera form a connecting link with the more highly evolved forms. In the first, _Acroscyphus sphaerophoroides_, the fronds are somewhat similar to the fertile ones of _Tholurna_, but they possess a solid central strand and the apical mazaedium is less enveloped by the thallus. The other, _Pleurocybe madagascarea_, has narrow flattish branching fronds about 3 cm. in height, hollow in the centre and corticate with marginal or surface fruits.