1921] : MILES—LEAF SPOTS OF ELM 163 
the Rocky Mountains, but has not been reported. In addition to 
the normal host, U. americana, specimens have been examined on 
U. fulva, U. alata, U. crassifolia, and U. racemosa, and it is quite 
probable that it may occur also on U. serotina, the only other 
American species. It has not been seen on any European or other 
foreign elm, however, collected either in this country or abroad, 
nor is there any account in literature of its occurrence on such. It 
may be concluded, therefore, that this ences is strictly an Ameri- 
can species. 
The fungus was first described 6 SCHWEINITZ (34) as Xyloma 
ulmeum, in 1818, on leaves collected at Aiken, South Carolina. 
His material was immature, and consequently his description was 
incomplete and inadequate. Fig. 7 is a leaf from the type collec- 
tion from which his description was taken. This specimen is one 
of SCHWEINITz’ exsiccati in the Museum of the Academy of Natural 
Sciences at Philadelphia. Comparison of this figure with figs. 3-5, 
showing infected leaves collected by the writer, indicates that the 
fungus with which ScHwernitz worked and the one discussed in 
the early part of this paper are identical. 
A few years after SCHWEINITz’ original description, Fri RIES (19) 
described a disease of the American elm as caused by Sphaeria 
ulmea Fr., but gave Xyloma ulmeum Schw. as a synonym, showing — 
that he bial seen SCHWEINITz’ previous description and recognized 
that he was dealing with the same organism. His description 
added but little to the earlier one of ScHwErmitz. The next change 
in the taxonomic position of the fungus was made in 1878 by 
VON THUMEN (39) when he placed it in the genus Gnomonia with- 
out explanatory comment or additional description. In his 
Sylloge Fungorum SAccarDo seems to have accepted this change 
with some reservations, since he placed the fungus in the section 
Dubiae of the Sphaeriales, under the name Gnomonia ulmea 
(Schw.) ‘Thiim., without, however, explaining his reasons for 
doing so. 
In 1892 Exzis and Evernart (16) made a further change in 
the name and taxonomic position of the fungus, apparently with- 
out being acquainted with the previous work of von THUMEN, 
since they made no mention either of his name or of Gnomonia in 
