LICHENS AND FUNGI OF OTAGO, NEW ZEALAND. 445 



The cephalodia of Usnea are not mentioned by Mudd (Manual, 1861) ; but they 

 appear to have been familiar to the earlier English Lichenologists, who con- 

 tributed to the " English Botany" of Sir James E. Smith. In that work they are 

 both figured and described, apparently as of a twofold character, viz., partly as 

 " orbillce" or abortive apothecia, partly as " warts" or excrescences (p. 71). The 

 " orbillse" are best marked and commonest in var.jlorida, L. (p. 71, plate 2250). 

 They agree in aspect with the cephalodia of U. longissima, Ach., from Sikkim 

 (Himalayas) in the Hookerian Herb., Kew. In var. hirta, Fr., they are described 

 as " flesh-coloured, solid warts" (p. 72, plate 2252) ; and in the type U. barbata, 

 Fr., as " fleshy tubercles or warts." The writer adds in regard to the latter 

 (the type U. barbata) a reference to the "absence of 'orbillse,' which have never 

 yet been discovered upon it in Britain or elsewhere" (p. 72, plate 2253) : thus 

 drawing an unnecessary distinction between the " warts" and " orbillse," which 

 are evidently, nevertheless, of essentially the same nature. 



Rabenhorst appears to regard the cephalodia affected by the parasitic Abro- 

 thallus as a diseased condition of the apothecia of the Usnea. But the latter, in 

 their normal condition, are large, handsome, flat, broad, peltate ; with a disk of 

 similar colour to the thallus, or pale flesh-coloured as in Ramalina, the margin 

 fringed with cilia, having the characters of the ultimate thalline ramuscles. In 

 exceptional cases (as in a specimen of var. florida lately sent me from Lagos, 

 West Africa, E. L. Simmonds) the apothecium is Parmelioid ; the disk red and sub- 

 urceolate ; the margin raised, and furnished with few and short cilia, or sub- 

 simple. Here the apothecia are seated at angles of the thalline ramules, a cir- 

 cumstance which, though common or general in cephalodia, is rare in apothecia. 

 .Exceptionally cephalodia are apotheciiform — that is, they are flattish, with a 

 raised, generally thickish margin, the parasite occupying the cavity resembling 

 the disk. But I have never been able to trace any distinct transition between 

 cephalodia and apothecia ; hence I regard them as essentially differing in character 

 and function. The cephalodia so common on the genus Usnea may be regarded 

 as analogous to those of Stereocaulon (Nyl. Syn. 15), save that in Usnea they are 

 solid, while in Stereocaulon they are hollow ; in both cases, they must be con- 

 sidered morbid growths of and from the cortical layer of the thallus. In Usnea, 

 they usually have the aspect of Cladonioid or Biatorine, compound or confluent, 

 apothecia ; being irregularly tuberculated, and more or less of a pale brownish 

 or flesh-colour. Almost universally, where they occur, they produce angularity of 

 the thalline ramules, so that they appear to have their normal seat at natural 

 angles of the branchlets. The cephalodia are abundant all over the plant; so that 

 in regard to their site, they are in marked contrast to the normal apothecia of 

 Usnea. In Sikkim specimens of U. longissima I have found cephalodia terminal 

 on two of the divergent cilia or fibrillar of the thallus ; in which case they had 

 greatly the aspect of Cladonioid apothecia. 



