_e._ SPECIES WITHOUT SCYPHI. In species where the whole summit of the podetium is occupied by an apothecium, as in _Cl. bellidiflora_, no scyphus is formed. There is also an absence of scyphi in podetia that taper to a point. In those podetia the hyphae are parallel to the long axis and remain in connection with the external gonidial layer so that they are unaffected by the central cavity. Instances of tapering growth are also to be found in species that are normally scyphiferous such as _Cl. fimbriata_ subsp. _fibula_, and _Cl. cornuta_, as well as in species like _Cl. rangiferina_ that are constantly ascyphous. The scyphus is considered by Wainio[400] to represent an advanced stage of development in the species or in the individual, and any conditions that act unfavourably on growth, such as excessive dryness, would also hinder the formation of this peculiar lichen structure. D. BRANCHING OF THE PODETIUM Though branching is a constant feature in many species, regular dichotomy is rare: more often there is an irregular form of polytomy in which one of the members grows more vigorously than the others and branches again, so that a kind of sympodium arises, as in _Cl. rangiferina_, _Cl. sylvatica_, etc. Adventitious branches may also arise from the podetium, owing to some disturbance of the normal growth, some undue exposure to wind or to too great light, or owing to some external injury. They originate from the gonidial tissue in the same way as does the podetium from the primary thallus; the parallel hyphae of the main axis take no part in their development. In a number of species secondary podetia arise from the centre of the scyphus—constantly in _Cl. verticillata_ and _Cl. cervicornis_, etc., accidentally or rarely in _Cl. foliacea_, _Cl. pyxidata_, _Cl. fimbriata_, etc. Wainio[401] has stated that they arise when the scyphus is already at an advanced stage of growth and that they are to be regarded as adventitious branches. The proliferations from the borders of the scyphus are in a different category. They represent the continuity of apical growth, as the edges of the scyphus are but an enlarged apex. These marginal proliferations thus correspond to polytomous branching. In many instances their advance is soon stopped by the formation of an apothecium and they figure more as fruit stalks than as podetial branches. E. PERFORATIONS AND RETICULATION OF THE PODETIUM Perforations in the podetial wall at the axils of the branches are constant in certain species such as _Cl. rangiferina_, _Cl. uncialis_, etc. They are caused by the tension of the branches as they emerge from the main stalk. A tearing of the tissue may also arise in the base of the scyphus, due to its increase in size, which causes the splitting of the diaphragm at the bottom of the cup.