BRITTON: FLORA OF THE VIRGIN ISLANDS 



111 



vel albo-cinerascens, tenuis laevis subcontinuus. Apothecia sessilia nuda ad 0.8 

 mm. lata, primum orbicularia suburceolata, margine crenato, dein orbicularia 

 oblonga vel subdifformia, disco late aperto piano rugoso atrofusco, margine laciniato 

 partim stellato-radiato nitido nigro; epithecio fusco; hymenio incolore, 120-130 /^ 

 altit. ; hypothecio incolore; amphithecio sub lamina deficiente, cetero crasso nigro. 

 Paraphyses firmae crassae ramosae haud connexae. Asci cylindrices, 8-spori. 

 Sporae incolores aciculares rectae vel subflexuosae vel rarius contortae, 20-24- 

 loculares, cellulis cylindricis, 60-100 x 2-3 /u. 



Fig. I. Opegrapha actcularis Riddle. Vertical section of apothecium (stippling 

 indicates dark coloration); paraphysis; ascus with two of the eight spores. 



On bark of Erythroxylon, Punta Aguila, Porto Rico, collected by 

 N. L. Britton, J. F. Cowell, and Stewardson Brown, Feb. 27, 1915, 

 no. 4682 (type!). Also, on Guilandina, Smith's Bay, St. Thomas, 

 1276a, 1279; and on Coccolobis, Great Harbor Cay, Berry Islands, 

 Bahamas, N. L. Britton and C. F. Millspaugh, no. 2545. 



This is a striking and distinct species belonging to the section 

 Pleurothecium of the genus Opegrapha. Externally it is easily recog- 

 nizable by the marked tendency for the laciniate margin of the apo- 

 thecia to spread out in a stellate manner. The spores resemble those 

 of Lecanactis myriadea (Fee) Zahlbr. and of Opegrapha pleistophrag- 

 moides Nyl. But both of the species named have the black amphi- 

 thecium complete at the base, and the spores are almost twice as 

 thick. 



24. Opegrapha agelaea Fee. On Crescentia, Tutu, 462. Cuba, 



Colombia. 



25. Opegrapha atra Pers. On Guilandina, Smith's Bay, 1278a; on 



Melicocca, Smith's Bay, 1285. 



