8 ILLINOIS BIOLOGICAL MONOGRAPHS [476 



The following summary will serve to give a general idea of the scope 

 of the present report : 



Total number of collections of Meliola 729 



Number of species of Meliola 95 



" varieties of Meliola 6 



' ' new species of Meliola 56 



" new varieties of Meliola.. _ 6 



** species and varieties of Meliola new to Porto Rico 83 



" species and varieties of Meliola previously reported 



from Porto Rico 20 



" hosts 171 



" " previously reported _ 25 



" " new to Porto Rico for Meliola 146 



" host families 53 



" " '* previously reported 18 



" " " new to Porto Rico for Meliola 35 



In grouping the genus into sections and in keying the species I have 

 in the main followed the plan adopted by Gaillard, laying principal 

 emphasis upon the setae, perithecial and mycelial, next upon the char- 

 acter of the setal tips, and basing final specific distinction upon more 

 minute characters of mycelium, capitate hyphopodia, spore, etc. It is 

 to be noted that in Porto Rico occur none of the species with clavate, 

 long, 8-spored asci. All are of the short-ascus form with two to four 

 spores per ascus. In certain species there is constancy as regards each 

 character, in other species there is large variation. Young colonies may 

 be devoid of mycelial setae though they may be abundant in old colonies 

 (M. earlii). Certain species sometimes though not always present perithe- 

 cial setae (M. solani). Several species show large variation as to setal 

 tips, the tips being sometimes simple and acute, sometimes slightly 

 forked, (M. mangiferae, M. ipamoeae), even much forked, and all aris- 

 ing from the same mycelium; or the forking may show a great range 

 in character and complexity (M. furcata). In other species the setal 

 tips may show great constancy, e.g., M. cucurhitacearum. Taken all in 

 all the problem of specific limitation is much the same as is met in the 

 Erysiphaeeae, with very similar characters to use. 



The problem of classification is rendered especially difficult by the 

 fact that the Meliolas are very often overgrown by parasites which con- 

 fuse the picture and also often prevent the formation of perithecia, and, 

 I believe, strongly influence the character of the mycelium and hypho- 

 podia, i.e., the mycelium and hyphopodia are often made more crooked 

 and more angular, or to appear so, by the parasite that is growing upon 

 them. I believe also that the character of the mycelium is strongly 



