The thallus of Stictaceae has been regarded by Nylander[424] and others as one of the most highly organized, not only on account of the size attained by the spreading lobes, but also because in that family are chiefly found those very definite cup-like structures which were named “cyphellae” by Acharius[425]. They are small hollow depressions about 1/2 mm. or more in width scattered irregularly over the under surface of the thallus. _a._ HISTORICAL. Cyphellae were first pointed out by the Swiss botanist, Haller[426]. In his description of a lichen referable to _Sticta fuliginosa_ he describes certain white circular depressions “to be found among the short brown hairs of the under surface.” At a later date Schreber[427] made these “white excavated points” the leading character of his lichen genus _Sticta_. In urceolate or proper cyphellae, the base of the depression rests on the medulla; the margin is formed from the ruptured cortex and projects slightly inwards over the edge of the cup. Contrasted with these are the pseudocyphellae, somewhat roundish openings of a simpler structure which replace the others in many of the species. They have no definite margin; the internal hyphae have forced their way to the exterior and form a protruding tuft slightly above the surface. Meyer[428] reckoned them all among soredia; but he distinguished between those in which the medullary hyphae became conglutinated to form a margin (true cyphellae) and those in which there was a granular outburst of filaments (pseudocyphellae). He also included a third type, represented in _Lobaria pulmonaria_ on the under surface of which there are numerous non-corticate, angular patches where the pith is laid bare (Fig. 72). Delise[429], writing about the same time on the _Sticteae_, gives due attention to their occurrence, classifying the various species of _Sticta_ as cyphellate or non-cyphellate. Acharius had limited the name “cyphella” to the hollow urceolate bodies that had a well-defined margin. Nylander[430] at first included under that term both types of structure, but later[431] he classified the pulverulent “soredia-like” forms in another group, the pseudocyphellae. As a rule they bear no relation to soredia, and algae are rarely associated with the protruding filaments. Schwendener[432], and later Wainio[433], in describing _Sticta aurata_ from Brazil, state, as exceptional, that the citrine-yellow pseudocyphellae of that species are sparingly sorediate. [Illustration: Fig. 72. _Lobaria pulmonaria_ Hoffm. Showing pitted surface. a, under surface. Reduced (S. H., _Photo._).] [Illustration: Fig. 73. _Sticta damaecornis_ Nyl. Transverse section of thallus with cyphella × 100.]