Wainio has indicated the course of evolution on the following lines: (1) the crustaceous thallus is monophyletic in origin and here as elsewhere precedes the squamulose. The latter he considers to be also monophyletic, though at more than one point the more advanced and larger foliose forms have appeared: (2) the primitive podetium was subulate and unbranched, and the apex was occupied by the apothecium. Both scyphus and branching are later developments indicating progress. They are in both cases associated with fruit-formation—scyphi generally arising from abortive apothecia[1009], branching from aggregate apothecia. In forms such as _Cl. fimbriata_, where both scyphiferous and subulate sterile podetia are frequent, the latter (subspecies _fibula_) are retrogressive, and reproduce the ancestral pointed podetium. (3) In subgen. _Cenomyce_, with a squamulose primary thallus, there is a sharp division into two main phyla characterized by the colour of the apothecia, brown in _Ochrophaeae_—the colour being due to a pigment—and red in _Cocciferae_ where the colouring substance is a lichen-acid, rhodocladonic acid. In the brown-fruited _Ochrophaeae_ there are again several secondary phyla. Two of these are distinguished primarily by the character of the branching: (_a_) the _Chasmariae_ in which two or several branches arise from the same level, entailing perforation of the axils (_Cl. furcata_, _Cl. rangiformis_, _Cl. squamosa_, etc.), the scyphi also are perforated. They are further characterized by peltate aggregate apothecia, this grouping of the apothecia according to Wainio being the primary cause of the complex branching, the several fruit stalks growing out as branches. The second group (_b_), the _Clausae_, are not perforated and the apothecia are simple and broad-based on the edge of the scyphus (_Cl. pyxidata_, _Cl. fimbriata_, etc.), or on the tips of the podetia (_Cl. cariosa_, _Cl. leptophylla_, etc.). A third very small group also of _Clausae_ called (_c_) _Foliosae_ has very large primary squamules and reduced podetia (_Cl. foliacea_, etc.), while finally (_d_) the _Ochroleucae_, none of which is British, have poorly developed squamules and variously formed yellowish podetia with pale-coloured apothecia. The _Cocciferae_ represent a phylum parallel in development with the _Ochrophaeae_. The species have perhaps most affinity with the _Clausae_, the vegetative thallus—both the squamules and the podetia—being very much alike in several species. Wainio distinguishes two groups based on a difference of colour in the squamules, glaucous green in one case, yellowish in the other.