SÉANCE DU 22 OCTOBRE 1877. 315-XXIII 
Peridermium corticolum lias larger peridia, which are more inflated, 
not compressée! and containing pseudospores 0 mm ,020-0' mn ,024. 
Peridermium acicolum lias compressed peridia and elongated pseudo- 
spores which are from 0 ram ,032-0 mm ,040 X 0 mm ,020. 
Tliis appears to me sufficient groundsfor maintaining the two species as 
distinct. The P. cerebrum Peck, a North American form, is nothing more 
than a condition of P. corticolum. 
Recentlv I received from the Himalayas of India several forms of Peri¬ 
dermium ; and amongst them P. acicolum of the typical form on Pinus 
Smithiana; there was also another which externally resembled P. acico¬ 
lum, but witb the spores of P. corticolum. This I bave called P. orientale. 
Either this form unités the other two, as an intermediate condition, or 
else the three must be accepted as distinct species. The form called 
P. orientale occurred on the leaves of Pinus australis, Pinus longifolia, 
and Pinus excelsa. 
The next illustration is taken from the genus Rœstelia. The common 
R. cornuta Tul. is widelv known, but a very similar species sent to me as 
R. cornuta from North America, on the leaves of a species of Cratœgus, is 
neither lhat species nor R. lacer ata Tul., but, as I believe, quile a distinct 
species, which I bave called Rœstelia liyalina. The peridia are smaller 
and more délicate, pointed at the apex, and dehiscing by a longitudinal 
fissure throughout nearly their entire length. The cells of the peridia are 
smaller, mucli more délicate and without striation. A comparison of the 
two forms is only necessary to establish their daims to a distinct nomen¬ 
clature. 
Finally the genus Æcidium will furnish an example in the well known 
Æcidium Berberidis P. It need not be said that this is a very charade- 
ristic species, with the peridia very much elongated and clustered together 
on a thickened discolored spot. Many years ago Shuttleworth found near 
Berne in Switzerland an Æcidium growing on Rerberis vulgaris, which 
lie named Æcidium graveolens. It is characterized as having a peculiar 
odour when fresh, the peridia are scattered over the leaf without any 
thickened or discolored spots, they are also abbreviated, and the cells of 
the peridium, as well as the spores ditfer in size. These features seem to 
me to warrant the récognition of Æcid. graveolens Shutt. In order that 
ail these forms may be seen and studied at leisurc by the mycologists of 
France, the specimens exhibited will be placed in the herbarium at the 
Jardin des plantes at the close of this meeting. 
Après cette communication faite en langue anglaise par M. Cooke, 
M. Ilowse donne lecture de la traduction suivante : 
