316 SYSTEMATIC 



VII. PYRENULACEAE 



This family of crustaceous lichens differs from Verrucariaceae chiefly in 

 the gonidium which is a species of Trentepohlia. Genera and species are 

 largely corticolous and the thallus is inconspicuous, often developing within 

 the substratum; The perithecia, like those of Verrucariae, are immersed or 

 partly emergent and have an entire or dimidiate outer wall. They are 

 scattered over the thallus except in Anthracothecium where they are often 

 coalescent. This genus is tropical or subtropical except for one species 

 which inhabits S.W. Ireland. 



Paraphyses are variable, and in some species tend to disappear, but do 

 not dissolve in mucilage. The spores are generally colourless, only in one 

 monotypic genus, Coccotreina, are they simple. The cells into which the 

 spore is divided differ in form according to the genus. 



Paraphyses branched and entangled or wanting. 



Perithecia opening above by stellate lobes I. *Asteroporum Mull.-Arg. 



Perithecia opening by a pore. 

 Spores variously septate. 



Spore cells cylindrical or cuboid. 



Spores colourless, elongate or ovate i-5-septate 2. Arthopyrenia Massal. 



Spores colourless, filiform I -multi-septate 3. Leptorhaphis Koerb. 



Spores colourless, muriform 4. Polyblastropsis A. Zahlbr. 



Spores brown, ovoid or elongate 2-5-septate ... 5. Microthelia Koerb. 

 Spore cells globose or lentiform, 3-multi-septate 6. *Pseudopyrenula Miill.-Arg. 

 Paraphyses unbranched free. 



Spore cells cylindrical or cuboid. 



Perithecia beset with hairs 7. *Stereochlamys Miill.-Arg. 



Perithecia naked. 



Asci disappearing ; spores elongate multi- 

 septate, colourless 8. *Belonia Koerb. 



Asci persistent. 



Spores simple, ellipsoid, colourless 9. *Coccotrema Miill.-Arg. 



Spores elongate, i -multi-septate, colourless... 10. Porina Miill.-Arg. 



Spores elongate, i -multi-septate, brown u. Blastodesmia Massal. 



Spores muriform, colourless 12. *Clathroporina Miill.-Arg. 



Spores elongate, 2-3-septate, colourless 13. Thelopsis Nyl. 



Spore cells globose or lentiform. 



Spores elongate, i-5-septate, brown 14. Pyrenula Massal. 



Spores muriform, brown 15. Anthracothecium Massal. 



VIII. PARA THELIACEA E 



This family is peculiar in that the perithecia open by a somewhat 

 elongate ostiole that slants at an oblique angle. The algal cells are Trente- 

 pohlia. Genera and species are endemic in tropical or subtropical regions 

 of the Western hemisphere, though a species of Pleurotrema has been found 

 in subantarctic America. They are corticolous and the thallus is either 



