vi PREFACE 
“ Monographia,” where a complete synonymy, with dates, lies 
at the disposal of those who are interested in that matter. 
A plan has been adopted, in a few cases, of grouping 
some forms that are closely allied under a common name; 
see Puccinia dispersa and P. sessilis, With more knowledge 
(or more courage) this process might have been carried much 
farther, and it is believed that in this device will be found the 
first line of defence of sane systematists against the excessive 
multiplication of “species” by “biological” nomenclators. It 
cannot be justifiable to use the same word in the same branch 
of science to denote two widely diverse grades of evolution. 
Physiological, unaccompanied by morphological, distinctions 
should never be allowed to constitute a difference of species, 
unless it be as a temporary measure in cases which have not 
been investigated. 
In selecting the name for each species, the principle of 
priority has been followed, subject to two conditions—(1) names 
given to varieties need not be adopted (International Rules, 
1905, Art. 49), and (2) names given to imperfect states are 
not to be preferred, but the earliest name given to the perfect 
(in this case, the teleutospore) stage (Brussels Congress, 1910); 
sometimes, however, the name Uredo may have included the 
perfect stage, as in some species of Uromyces (U. Scirpi, etc.). 
Since ecidiospores are almost always “ rounded-polygonal,” 
their shape is not mentioned unless it deviates from this form. 
In the systematic part, all the spores are drawn to the same 
magnification (600 times), except where indication to the 
contrary is given. The drawings are all original and from 
British specimens, unless a different source is stated. When 
several similar spores are outlined, the surface-sculpture is not 
always indicated upon every one of them. 
My thanks are especially due to Professor G. S. W est, by 
whose advice this work was undertaken and by whose assistance 
it has been chiefly carried through. The ‘Plow right’ Herbarium 
of Fungi, which is in the possession of the University, has been 
