322 Proceedings of hidiana Academy of Science 



all three are almost identical and have similar spores. While one of the 

 chief generic characteristics of Daldinia is the concentric layers of its 

 stroma, we have a rather common species of Hypoxylon whose most 

 noticeable characteristic is that of concentric stromatic layers. It fol- 

 lows that a student learns these similar fungi as individuals rather than 

 by following a key to genera and species. Concerning Nummularia, 

 Ellis and Everhart say: "The genus is too closely allied to Hypoxylon, 

 especially the discoid forms." 



Among the imperfect fungi, a group in which the writer is par- 

 ticularly interested, genera seem to have been formed for convenience 

 in many cases and we have been led into species multiplicity and count- 

 less errors. 



As an example, we cite the common genera, Phyllosticta, Phoma and 

 Macrophoma. When the first two were set apart, their only difference 

 was that of habitat. If on a leaf, it was Phyllosticta; if on any other 

 part of a plant, it was a Phoma. When one considers the similarity of 

 a young shoot and a leaf, he wonders why such a division was ever 

 made. Furthermore, those species of the genus Phoma having spores 

 more than fifteen microns long, were placed in a separate genus, Macro- 

 phoma, this arbitrary difference in spore length sufficing for a new genus. 



The entire group of imperfect fungi abounds in similar examples. 

 In the Hyphomycetes, the group with scattered and tufted conidiophores 

 is separated into the families Mucedinaceae and Dematiaceae entirely 

 on the basis of mycelium color, yet this basis was not used in separating 

 the Stilbaceae and Tuberculariaceae. 



It is to be noted also that genera have been based upon spore shape. 

 In the classification group known as Scolecosporae, a s^pore must be 

 long in proportion to its width. But just what proportion? While a 

 standard of proportion may be attained by long study of the groups, 

 the actual determination, left to the individual, has resulted in the 

 placing of those fungi with spores of intermediate proportion in the 

 group which suits the judgment of the individual. As a result, a 

 student must seai-ch through several genera to locate his plant. A 

 spore size limit as in the case of Phoma and Macrophoma would be 

 preferable. 



The common practice of forming sub-groups of any kind for the 

 purpose of classification where the groups are large and unwieldy, has 

 in many cases, resulted in the establishing of many doubtful or peculiar 

 genera. 



