'iii
lit
Æ . Thalidri, on the genus Roestelia of L i n k , whose generic ,
character is,
“ Acervi sporidiorum epidermidem rumpunt forma tubulosa excreseen-
tem. Sporidia subglobosa, libera."
Under this iie brings the subject o f the present description, as
well as several others exactly intermediate between it and the
common form of Æ c id ia . S c h m id t and K u n z e , in their
very useful work tlie “ Deutschlands Schwaemme,” have given
a very different generic character for Roestelia, viz. “ Peridium
filis parallelis apice cohærentibiis compositum e stromate pro-
grcdiens. Pnlvis farinacens nudus.” Such species as Æ c idium
cancellatum and Æ . laceratum, &c. whose structure is
decidedly filamentous, may indeed be entitled to a separation
from the other Æ c id ia .
U i i . '
Fig. 1. A leaf o f Sorbus Aucuparia, with Æcidium cornutum, nat. rize
Part o f a chiste)- o f peridia, magnifed. Fig. 3. Sporidia.
Fig. 2.
M i l
