FAMILIES AND GENERA 323 



Thallus with Trentepohlia gonidia. 

 Paraphyses free, unbranched. 



Spore cells short or almost globose. 



Spores elongate, multi-septate, colourless i. Glyphis Fde. 



Spores elongate, multi-septate brown 2. *Sarcographa Fde. 



Spores muriform, brown 3. *Sarcographina MUU.-Arg. 



Spore cells longer and cuboid. 



Spores muriform, colourless 4. *Enterodictyon Miill.-Arg. 



-Paraphyses branched, interwoven above. 



Spores elongate, multi-septate, colourless 5. Chiodecton Ach. 



Spores elongate, multi-septate, brown 6. Sclerophyton Eschw. 



Spores muriform, colourless 7. *Minksia Miill.-Arg. 



Spores muriform, brown 8. *Enterostigma Miill.-Arg. 



Thallus with Phycopeltis gonidia (epiphyllous). 

 Paraphyses free. 



Spores unequally 2-celled, colourless 9, *Pycnographa Miill.-Arg. 



Paraphyses branched, interwoven above. 



Spores elongate, multi-septate, colourless 10. *Mazosia Massal. 



XXI. DiRINACEAE 



A small family, which is associated with and often included under 

 Graphidaceae. The thallus is crustaceous and corticate on the upper 

 surface, the cortex being formed of palisade hyphae. Algal cells Tretite- 

 pohlia. Apothecia are rounded or with a tendency to elongation, and, in 

 addition to a thin proper margin, possess a stout thalline margin ; the 

 hypothecium is thick and carbonaceous. There are two genera : Dirina 

 with twelve species has a wide distribution ; Dirinastruvi is monotypic and 

 occurs on maritime rocks in Australia. In both the spores are elongate- 

 .septate, differing only in colour: 



Spores colourless i. Dirina Fr. 



Spores brown 2. *Dirinastrum MilU.-Arg. 



XXII. ROCCELLACEAE 



The Roccellaceae differ from the preceding Dirinaceae chiefly in the 

 fruticose thallus which is more or less characteristic of all the genera, though 

 in Roccellographa it expands into foliose dimensions and in Roccellma is 

 reduced to short podetia-like processes from a crustose base. The fronds — 

 mostly long and strap-shaped — are protected in most of the genera by 

 a cortex of compact palisade hyphae; in a fe^^• the outer hyphae are parallel 

 with the long axis. The medulla is of parallel hyphae, either loose or 

 compact. The algal cells are Trentepohlia. 



The apothecia are lateral except in Roccellina where they occur at the 

 tips of the short upright fronds, and only in Roccellaria is there no thalline 

 margin. They are superficial in all of the genera except Roccellographa, in 

 which they are immersed and almost closed, recalling the perithecia-like 



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