314 SYSTEMATIC 



III. Verrucariaceae 



In all the genera of this family the thallus is crustaceous, and, with very 

 few exceptions, the species are saxicolous or terricolous. The thallus is 

 variable within the crustaceous limits, and may be superficial and very 

 conspicuous, almost imperceptible, or wholly immersed in the substratum. 

 The algal cells are Protococcaceae, and in two of the genera the green cells 

 penetrate the hymenium and grow in rows alongside of the asci. The 

 perithecia are small roundish structures scattered over the thallus, the base 

 immersed, but the upper portion generally projecting. An outer dark- 

 coloured wall surrounds the whole perithecium (entire) or only the upper 

 exposed portion (dimidiate) ; it opens above by a pore or ostiole more or 

 less prominent. 



In some of the genera the paraphyses become dissolved at an early 

 stage, and somewhat similar filaments near the ostiole, termed periphyses, 

 aid in the expulsion of the spores. The spores vary in septation, colour 

 and size, and these variations have served to delimit the genera which 

 have been formed from the original very large genus Verrucaria. The ascus 

 may be 1-2-, 4- or 8-spored. In only one genus is it many-spored 

 ( Trimmatothele). 



The genera are as follows : 



Perithecia with simple ostioles. 

 Paraphyses disappearing early, or wanting. 



Spores simple, ellipsoid i. Verrucaria Web. 



Spores simple, elongate vermiform 2. Sarcopyrenia Nyl. 



Spores simple, numerous in the ascus 3. *Trimmatothele Norm. 



Spores 1-3-septate 4. Thelidium Massal. 



Spores muriform (with transverse and longitudinal divisions). 



Without hymenial gonidia 5. Polyblastia Massal. 



With hymenial gonidia 5. Staurothele Norm. 



Paraphyses present. 

 Spores simple. 



Without hymenial gonidia 7. Thrombium Wallr. 



With hymenial gonidia 8. *Thelenidia Nyl. 



Spores 3-septate, broadly ellipsoid 9. *Geisleria Nitschke. 



Spores acicular, many-septate 10. Gongylia Koerb. 



Spores muriform 11. Microglaena Lonnr. 



Perithecia with a wide ring round the ostiole. 



Spores muriform; paraphyses unbranched 12. *Aspidothelium Wain. 



Spores elongate, many-septate; paraphyses branched 13. *Aspidopyrenium Wain. 



IV. Dermatocarpaceae 



In this family there is a much more advanced thalline development — 

 generally squamulose or with some degree of foliose structure, though in 

 the genus Endocarpon, some of the species are little more than crustaceous. 



