32 Transactions. 
necessary to maintain form-genera to contain these. Again, in any coun- 
try where little or no cultural work has been performed (as in New Zealand 
and Australia) many of these forms appear in systematic pepon dealing 
with the Uredinales. It is usual to assume, when a certain aecidium or 
uredo stage is regularly found in proximity with the Bestes that this 
(or these) form belongs to the cycle to which the teleutospores in question 
belong. This is not a safe practice to follow, and much caution is neces- 
h ; 
which later investigators have proved to belong to some entirely different 
fungus. Field investigations generally give some indication as to the = 
bable relationships of the forms found on the same or adjacent hosts, 
that in many cases it м а Nurs matter to supplement tlie 
ents. 
Five forms are generally recognized, as follows: Aecidium, Caeoma, 
Peridermium, Roestelia, and Uredo. Their characters may be summarized 
in the following ey: 
KEY ro ForM-GENERA. 
Spores catenulate 
Peridium present. 
On a о; zx xi x .. Peridermium. 
On Angiosperm ; 
Epispore pvo ed brown: germ-pores conspicuouse .. Roestelia. 
ч pes ~~ or tinted n germ: pores indistinct Aecidium. 
Peridium .. Caeoma. 
‘Spores borne shige on distinct. pedicels ; .. Uredo. 
Of these form-genera two only are алаа in this paper. Peridermdum 
occurs in the pe of Coleosporium, Cronartium, and Melampsoridium ; it 
is confined to the Coniferae. Roestelia occurs only in the cycle of Gymno- 
€—— E edades into Aecidiwm, but is separated on account of the 
horn-like p brown-coloured epispore, and conspicuous germ-pores. 
Caeoma souks in ihe cycle of Phragmidium, Melampsora, and Gymnoconia. 
It is characterized by the absence of a epus c: by the fact that the 
spores are catenulate ; in certain genera the mata are surrounded by 
paraphyses. Aecidium and Uredo are SLE more fully below. 
1. AEcrDIUM Persoon. 
Pers. in J. F. Gmel., Syst. Nat., vol. 2, p. 1472, 1791. 
0. rmogones immersed, flask-shaped, with protruding ostiolar fila- 
ments, honey-coloured, preceding or accompanying aecidia. 
I 
spots. Peridia hyaline, less frequently tinted yellow, margins erect or 
ecidiospores catenulate, polygonal, elliptical or subglobose ; epispore 
commonly hyaline, seldom tinted yellow, usually verruculose, with numerous 
scattered indistinct erm-pores. 
Distribution: World-wide. 
This form occurs in the cycle of certain species of Uromyces and 
. Puccinia. The mycelium is —— кое and usually causes etiola- 
tion and distortion of the host. As time атан s І hope to work out the 
cycles of all New Zealand Uredinales b P did of cultures, so that 
many of = forms listed a will ст be iier listed as synonyms. 
