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(fig. 7). The yellowish spores are subglobose (fig. 8), and in 
the first instance concatenate, or chained together like a neck- 
lace, which circumstance has been taken advantage of to place 
it, with one or two other species, in a separate genus. 
The desire to include illustrations of all the genera of uredo- 
like fungi within these papers, so as to render them useful to 
any desirous of commencing the study botanically as well as 
microscopically, necessitates brevity in description, and selec- 
tion in numbers, especially in this, the last to be devoted to 
them. Hence species may be met with in the fields and 
hedges not to be found in these pages, which are not intended 
as a flora, but rather as an introduction to one. The old 
genus Uredo , under which all the species alluded to in this 
contribution would then have been included, is now much less 
formidable in its dimensions ; nevertheless, we must rest con- 
tent with a reference to two or three species. Let the first 
bright day in May witness the student beside a cluster of 
plants of Mercurialis perennis } which it will not be difficult to 
find in many localities, and, on turning up the lower leaves he 
will meet with our first illustration of a genuine Uredo , in the 
form of yellow confluent patches, with a powdery surface 
(Plate XII. fig. 1). This will be Uredo confluens. By the way, 
the generic name is in itself suggestive, which it always should 
be in all instances, but unfortunately is not ; it is derived from 
the Latin word uro, “ I burn/* and is peculiarly applicable in 
instances where the leaves acquire a blistered, burnt, or 
scorched appearance, occasioned by the presence of the 
fungus. The microscopical features of the spores of this 
genus are, briefly, a more or less spherical form, without any 
pedicel or footstalk. These spores are at first produced each 
in a separate cell, but when ripe become free, and are at times 
with difficulty distinguished from such forms as Trichobasis , 
unless the pedicels in the early stage of the latter genus are 
regarded. 
A rare species in Britain is the oak-leaf rust ( Uredo Quercus ), 
in which the sori or pustules are minute, and at first yellow, 
but afterwards orange. It occurs on the under surface of the 
leaves, and was, I believe, first found in this country by Mr. 
D. Stock, in the neighbourhood of Bungay, nearly five-and- 
twenty years since. That gentleman informs me that it was 
not at all uncommon, but always appeared on the young shoots 
which had sprung up from the trunks or roots of trees that 
had been cut down. I am uncertain whether it has been found 
by any one since that time in this country, although it is not 
uncommon in France. 
The leaves of the common sorrel are often sparely sprinkled 
with the pustules of a rust ( Uredo bifrons , Grev.), which derives 
