PYRENULACEAE. 



523 



3. Verrucaria muralis Ach. Meth. Lieh. 115. 1803. 



On limestone, New Providence : cosmopolitan. 



4. Verrucaria nigrescens Pers. in Usteri, Ann. Bot. 14: 36. 1795. 



On limestone, New Providence : North America and Europe. 



Family 2. PYRENULACEAE. 



Spores plurilocular (two to many-celled). 

 Spores colorless. 



Spores with cylindrical cells. 



Paraphyses simple and persistent. 

 Paraphyses branched or deliquescent. 

 Spores with lens-shaped or rounded cells. 

 Spores brown. 



Paraphyses simple and persistent. 

 Paraphyses branched or deliquescent. 

 Spores muriform-multilocular. 

 Spores colorless. 



Paraphyses simple and persistent. 

 Paraphyses branched or deliquescent. 

 Spores brown. 



1. PORINA Ach. 



Perithecial wall entirely black. 



Thallus chalky-white ; perithecia 0.6-0.8 mm. in diameter. 

 Thallus greenish or purplish ; perithecia 1.01.5 mm. in di- 

 ameter. 



Perithecial wall black at the tip only, or not at all. 

 Thallus subfoliose, on rocks. 



Thallus with loosely adherent, convex lobes. 

 Thallus closely adnate, flat and merely crenate. 

 Thallus crustose, on bark. 

 Ostiole brown or reddish. 

 Ostiole blackening. 

 Spores 7-15 wide. 

 Spores 4-6 , wide. 



Thallus marked with frequent black lines. 

 Thallus without such lines. 



1. For i ltd. 



2. Arthopi/rcnia. 



3. Pseudopyrenula. 



4. Pyrcnulu. 



5. Microihelia. 



6. Clatliroporina. 



7. PolyMastlopsis. 



8. Anthracotheciuin. 



1. P. Wilsonii. 



2. P. macrocarpa. 



3. P. firm ula. 



4. P. subfirmula. 



5. P. nucula. 



6. P. mastoidea. 



7. P. variegata. 



8. P. Tetracerae. 



1. Porina Wilsonii Riddle, sp. nov. 



Thallus epilithieus crustaceus uniformis effusus baud limitatus, cretaceo- 

 albus opacus tartareus, erassiusculus continuus laevigatus, spermagoniis eopiose 

 nigropunctatus. Gonidia chroolepoidea. Perithecia globosa Integra nigra, 

 0.6-0.8 mm. lata, primum tota immersa maculis nigrescentibus indicata dein 

 semiemergentia, alte convexa, strato tenue thallode fere ad instar pruinae 

 velata, demum apicibus denudatis, ostiolis minutis umbonatis, nunquam elabentia. 

 Paraphyses persistentes tenues simplices. Asei cylindrices 8-spori. Sporae in 

 ascis uniseriales, incolores fusiformes 4-loculares loculis cylindricis, 13-15 X 4-5 /*. 

 Spermagonia minuta nigra apicibus emergentibus denudatis. Spermatia recta 

 bacillaria, 3-5 X I/". 



On limestone, Caleta Cocodrilos, Isle of Pines, Cuba (Britton, Wilson, and Leon, 

 March 8, 1916, 152S8, type). 



Bahamas : on limestone, New Providence (Brace, 9634) ', Governor's Harbor, 

 Eleuthera (Britton and Millspaugh. 5535). A lichen occurring near the Columbus 

 Monument, Watling's Island, and showing spermagonia only, agrees with this species, 

 but the determination can not be considered certain. 



This species, which I take pleasure in naming in honor of Mr. Percy Wilson, 

 may be distinguished from other species of the section Sagedia, to which it belongs, 

 by 'the chalky-white, tartareous thallus, and the delicately pruinose perithecia. It 

 bears a strong external resemblance to Verrucaria mamillaris, but can, of course, 

 be at once distinguished by the spores. 



2. Porina macrocarpa Riddle, sp. nov. 



Thallus epilithieus crustaceus uniformis effusus linea nigra limitatus, 

 glaucus virescens aut purpurascens opacus, crassitudine mediocris aut tenuis, 



