36 ILLINOIS BIOLOGICAL MONOGRAPHS [504 



Head cell cylindrical or only 

 very slightly thickened 

 Mycelium and hyphopodia not 



irregular ^I. lucumae No, 68 



Mycelium and hyphopodia 



irregular ^I. amiphitrieha No. 69 



Head cell ovate or elliptical 



Setae very long, 1000/x M. byrsonimae No. 70 



Setae not so long 



Setae very numerous ' M. tabernaemontana 



No. 71 

 Setae less numerous 

 Tips dark 

 Setae straight M. ambigua No. 72 



Setae curved M. pauUiniae No. 61 



Tips pale 



Head cell elliptical M. psychotriae No. 73 

 Head cell broader 



Spores small, 35/1, M. mayepeicola No. 74 

 Spores large, 60/x M. clusiae No. 75 



M. guareae found under section G., if the rare forked setae be 

 overlooked, might be sought in this section. 



The species of this section offer, perhaps, the greatest difficulty of 

 classification of all of the Meliolas because of .the very large number of 

 forms which fall within the section and the few characters involved. 

 Chief dependence for specific characterization must be placed upon the 

 setae, mycelium, and hyphopodia, since differences are often wanting in 

 other characters. 



42. Meliola psroii Fr. 



Linnaea 5 : 549, 1830. 

 On Psidium guajava L. 



Yauco, Oct. 3, '13, 3120. San German, Dec. 12, '13, 5841. Maya- 

 guez, Oct. 31, '13, 3899, March 9, '13, 493, 6443. San Sebastian, Nov. 

 22, '13, 5202. Vega Alta, Nov. 13, 4183. Jajome Alto, Dec. 3, '13, 

 5642di, July 17, '15, 8377. Arecibo-Lares Road, June 21, '1^,7302. Dos 

 Bocas, below Utuado, July 8, '15, 8033. Vega Baja, July 2, '15, 7721. 

 Sabana Liana, Aug. 13, '15, 9377. Maricao, July 20, '15, 8860. Utuado, 

 6563. Jayuya, 3120&. 



Collected by Heller, No. 4360, near Mayaguez. 



The shape of the ascospores is the chief distinguishing character of 

 this species. The form is very common on the guava wherever it grows. 



