238 
Transactions of the Boyal Society of South Africa. 
were not known for the first forty-seven years of its occurrence in 
Europe ; then during an exceptional season in France abundant perithecia 
were formed, corresponding in every way to those of the American species^ 
Uncinula nccator. Possibly a similar occurrence may place beyond doubt 
the identity of the South African Oiclium Tuckeri, but meanwhile this, 
fungus is provisionally referred to U. necator. 
Two new species of Uncinula are described, both from the Transvaal, 
one from the Pretoria District and the other from the Zoutpansberg. The 
former on Ficus sp. is near U. Salicis, but differs in dimensions and in 
the number and character of the appendages, the wall of the latter being, 
distinctly scabrous in the lower half. 
The Uncimda on Pterocarjnts differs materially from the species- 
described by Salmon on the same host (U. incrassata). It comes nearer 
to U. tectona, but difiers considerably in the dimensions of perithecia, 
asci, and spores, and in the number of appendages. 
A fungus which cannot be separated from the common and widespread 
Erysi(p]ie Polygoni D.C., has been found on several plants belonging to> 
the Euphorbiaceae and one Tiliaceae. The mildew of the garden pea and 
the sweet pea, w^hich are fairly common, are probably to be referred to 
this species, but no perithecia have yet been found on either of their 
hosts. 
The disease on different members of the Order Cucurbitaceae is one of 
the most troublesome pests caused by this group of fungi. It occurs 
throughout the country, and unless preventive measures are employed it 
almost invariably attacks cucumber, marrow, and pumpkin plants at the 
flowering period. It is responsible for a considerable amount of pecuniary 
loss. This fungus and the tobacco mildew {Oiclium Tabaci) are both 
provisionally referred to as Erysiphc c ichor aceannn, Salmon having found 
the perithecia of this fungus in connection with both pests. 
Oiclium Tabaci occurs wherever tobacco is cultivated, and may attack 
the crop severely if the plants are at all crowded. 
Erysiplie graminis is not very prevalent, and in only one case is 
reported as causing any serious damage. 
The genus Microsphaera is not represented among the fungi collected 
up to the present. 
The Phyllactinia, which occurs on several hosts, cannot be distin- 
guished from the ubiquitous P. corylea (Pers.) Karst. The form on 
Conibretuiii is more vigorous, and bears larger perithecia with more^ 
appendages than that on RJius. On Vigna angustifolia, although 
numerous perithecia are formed, I have been unable to find mature asci, 
even in specimens collected in winter after the plants have been killed by 
frost. The characters of the perithecium, however, are undoubtedly those 
of P. corylea. 
