Thallus fruticose, forming small mats with intertangled lobes; dichotomously branched, the angles of branching wider than in C. islandica, the tips becoming turned back, the edges inrolled and not only canaliculate but occasionally the edges fusing to become tubular, the surfaces chestnut brown, shining, the margins wavy, occasionally dentate, with rare spinules which arc poorly developed; lacking pscudocyphellae or with few narrow and tiny pseudocyphellae on lower margins. Upper cortex prosoplectenchymatous, 25 μ thick, the outer 5-7 μ brown, the inner part hyaline; medulla white, dense, the algae in scattered glomerules 25-75 μ thick; lower cortex as the upper. Apothecia not seen.

Reactions: medulla K-, C-, KC-.

Contents: protolichesterinic and rangi-formic acids.

Growing among mosses in dry tundras, this is an amphi-Beringian species with a narrow range, being known from eastern Siberia and in the Aleutian Islands and Alaska Range as far east as Canoe Lake near the mouth of the Mackenzie River.