450 DR LAUDER LINDSAY ON THE 



of confluent perithecia, the plant forms most irregular blotches of a dark-brown 

 colour (figs. 49, 52 b). The parasite can scarcely be confounded with the spermo- 

 gonesof the Sticta. The latter are confined to the thalline rugae* (fig. 48 b), while 

 the parasite is irregularly and generally scattered over fossae and rugae alike (fig. 

 48 a). The spermogones are, moreover, paler brown, wholly immersed, punctiform, 

 and greatly more minute than the smallest or papillaeform condition of the para- 

 site. The latter occurs on the larger (sterile) darker-coloured, and more fossulate 

 forms of thallus ; while the spermogones are most distinct on paler and fertile 

 forms. I have found similar parasitic perithecia or papillae, isolated, variable as 

 to size, but containing neither spores, spermatia, nor stylospores, in Tasmanian 

 (and fertile) forms of S. fossulata, sent me by my friend M. C. Cooke. 



3. On S. rubella, Hook, and Tayl. (sterile specimens), on trunks of dead trees, 

 Greenisland Bush. 



In some specimens of the Sticta the thallus is covered with blackish or brown 

 blotches, apparently allied to the larger maculae described in No. 2. But here 

 they are not distinctly defined — the blotch gradually merging or fading into the 

 beautiful red colour of the thallus. Nor are they distinctly raised above the 

 thalline surface. Under the microscope, all the structure these blotches exhibit 

 consists of a brown or blackish-brown filamentous tissue, composed of jointed 

 cells, thick-walled, and varying much in length and breadth ; whereas the peri- 

 thecia, composing the maculae in S. granulata and S. fossulata, though they 

 exhibit no spores, possess a distinct envelope, consisting of small, irregular, 

 dark-brown, closely packed cells ; a structure which resembles that of the 

 conceptacle of the parasitic Microtlieliw (figs. 2G, 46). 



It remains for the Local Botanist to determine whether it is the same parasite, 

 which affects S. granulata, S. fossulata, and S. rubella ; whether all the forms of 

 Perithecia, Sori, and Maculae above described, are referable to a single plant, f 



Inasmuch as the parasite in all my Otago specimens was in an imperfect 

 (infertile) condition for description and determination, it is necessary, in order to 

 an approximate understanding of the nature and relations of the perithecia and 

 maculae referred to, to append some description of authentic and fertile condi- 

 tions of the nearest European species. Of these, the most closely allied which I 

 have seen appears to be — 



4. Celiclium Peketii, Hepp exs. 372 and 589. Parasitic on the thallus of Sticta 

 aurata, Ach. (S. aurata var. abortim, Schaer.) ; Brazil ; excellent specimens. 

 The maculae are so large and conspicuous, as well as so abundant, that the 

 thallus is prominently black-mottled to the naked eye. Typical (fertile) maculae 

 are regularly round ; convex or sub-conoid ; isolated ; of a deep blacki-sh-brown 

 colour; resembling in general aspect the apothecia of Arthonia lurida. In 



* Lindsay, Mem. Spermog. p. 198, plate x. figs. 26-7. 

 f Compare Sphceria homostegia, Nyl. 



