1851 PARASITIC FUXGI—STEVEXS 19 



13. Phyllachora congruens Rehm. 

 Leaflets Phillip, Bot., 6:2220, 1914. 

 On Valota laxa. 



Trinidad: Cumuto, August 16, 1922, 894. 



14. Phyllachora dimorphaxdrae Stevens n. sp. 

 [Figures 39 to 41, 96] 



Stromata black, shining above, dull below, very irregular in shape, 

 2 to 15 mm. across, arched above, the whole mesophyll occupied by a loose 

 stroma; clypeus on each surface. Clypeus 18 to 36 ix thick, epidermal and 

 subepidermal. Locules 30 per stroma, in one row, when young near the 

 upper leaf surface, but developing to fill the leaf space and opening hypo- 

 phyllous; very large and irregular, 390 to 520 x 179 to 310^. Asci 8-spored, 

 115 X 7/u, long-stalked. Paraphyses filamentous, gelatinous. Spores uni- 

 seriate, hyaline, continuous, oblong, obtuse, 7 to 11 .x 5/i. 



On Dimorphandra sp. 



British Guiana: Wismar, July 14, 1922, 291; Demerara-Essequibo R. 

 R., July 15, 1922, 333 (type); Kartabo, July 22, 1922, 629. 



More than fifty syecies of Phyllachora are listed by Theissen and Sydow 

 on the Leguminosae but all of these differ from this species in one or more 

 essential characters. 



The mycelium between the two clypei is very fine, hyaline and loosely 

 pervades the whole mesophyll region, somewhat darkening the host cells. 

 Each locule is lined by a layer of mycelium about XOfx thick thus consti- 

 tuting a very thin but no less actual perithecial wall (Figure 40). Not- 

 withstanding this the fungus is truly Dothideaceous in summation of 

 characters. The origin of the locules close to the upper part of the leaf 

 seems constant. As they enlarge they soon come to press against the epiphyl- 

 lous clypeus and as they mature they develop a beak-like protuberance 

 which presses through the mesophyll to the lower clypeus; breaks through 

 this and becomes osteolar. 



15. Phyllachora engleri Speg. 

 Guaranit. I. No. 267 On Anthurium sp. 



British Guiana: Coverden, August 5, 1922. 

 This remarkably beautiful specimen agrees closely with the published 

 descriptions. 



16. Phyllachora guianensis Stevens n. sp. 



Stromata oval, small, about 1 mm. long, scattered, black, shining, 



surrounded by a zone of dead brown tissue forming an oval spot 2 to 4 mm. 



in size. Aluch more commonly conspicuous above than below. Loculi 



globular, few in each stroma, usually not more than six, located strictly in 



